The classic Nikon F body had several viewfinder upgrades over the years. You could add different film backs, motors—and of course the lenses were interchangeable as well.

The idea of modular cameras is not new, has been proven to be marketable, and profitable.

The upgrades can be done without tools by consumers, or an upgrade program can be done back at the factory. Shouldn’t be much harder to unscrew a circuit board and put in a new one on a camera than to upgrade a processor on a computer, or change a SIM card on a cell phone. Not for everyone, sure, but plenty of people can do this.

You gave a textbook explanation of why products are no longer made that way. The company now has control over everything. The Nikon motor had to be installed by Nikon, though. With that attached, the camera could shoot at a "blazing" 7 fps.

Apple learned that people are willing to buy a new product rather than to upgrade. I can replace almost everything inside my 2012 iMac, but I can't replace anything in my 2022.

You gave a textbook explanation of why products are no longer made that way. The company now has control over everything. The Nikon motor had to be installed by Nikon, though. With that attached, the camera could shoot at a "blazing" 7 fps.

Apple learned that people are willing to buy a new product rather than to upgrade. I can replace almost everything inside my 2012 iMac, but I can't replace anything in my 2022.

Rather than meaningless hearsay... I actually had a Nikon D3x serviced by Nikon USA recently.
Top Tier (Level 3) Maintenance & Cleaning. They did a fantastic Job! Very Pleased...

I've noticed an alarming amount of misinformation on UHH.
Especially when it comes to Nikon's Service and Support.

Much of the posted "information" is simply not valid.
UHH has little if any credibility left in my minds eye.

Are you a Commercial Photographer?
If so here is valid authoritative information (Nikon's Terms and Conditions of Service)
https://www.nikonpro.com/TermsAndConditions.aspx
Although you must meet Nikon's Support Criteria

Bottom Line? Nikon is still providing Service and Support for both my D3x Pro Bodies and I've been extremely pleased with the quality of service and timely turnaround.

It's on you to determine if your Nikon camera model and serial number qualify...
And if you qualify for Nikon Professional Services.

That said if you are truly interested in discovering what it takes to work at the zenith of the Commercial Photography Industry, then please consider purchasing a flickr Pro membership...

It's not the tools folks it's the skill of the Carpenter that matters...
It is a poor Carpenter indeed that blames his tools for want of excellence.

BTW... Some folks strive to create their persona by the perceived retail worth of their current kit...
While those who shoot commercially know full well that their clients are impressed primarily by the quality of imagery of their deliverables... Form my experiences on UHH there seems to be a compelling need by hobbyist to seek validation from their UHH peers through their choice of camera platform vendor... Something I find totally lacking on flickr... go figure...

By far and away the very best investments I've made on my career journey is in enlisting the finest talent to collaborate with i.e. Hairstylist, Makeup Artist, Wardrobe Stylist and Lighting Assistants in my marketplace... Many of whom will provide their services and priceless expertise in exchange for the breathtaking imagery which Test Creatives can (and often do) produce.

I rarely ever have clients ask me about my kit...
While I virtually always have requests for references from former clients.

Maybe rethink establishing your persona from your kit and focus more on providing an exceptional Collaborative Team for your sessions. This has worked extremely well for my efforts albeit your results may be different..

Thoughts on Commercial Photography?
Your worth, credibility and professional reputation depend not only on your ability to create breathtaking publication quality imagery unrivaled by your competitors but also your ability to nurture and assist in development of other aspiring talent emerging within the industry.

Wishing each and everyone an epic Summer Solstice...

It's not the tools folks it's the skill of the Carpenter that matters...
It is a poor Carpenter indeed that blames his tools for want of excellence.

BTW... Some folks strive to create their persona by the perceived retail worth of their current kit...
While those who shoot commercially know full well that their clients are impressed primarily by the quality of imagery of their deliverables... Form my experiences on UHH there seems to be a compelling need by hobbyist to seek validation from their UHH peers through their choice of camera platform vendor... Something I find totally lacking on flickr... go figure...

By far and away the very best investments I've made on my career journey is in enlisting the finest talent to collaborate with i.e. Hairstylist, Makeup Artist, Wardrobe Stylist and Lighting Assistants in my marketplace... Many of whom will provide their services and priceless expertise in exchange for the breathtaking imagery which Test Creatives can (and often do) produce.

I rarely ever have clients ask me about my kit...
While I virtually always have requests for references from former clients.

Maybe rethink establishing your persona from your kit and focus more on providing an exceptional Collaborative Team for your sessions. This has worked extremely well for my efforts albeit your results may be different..

Thoughts on Commercial Photography?
Your worth, credibility and professional reputation depend not only on your ability to create breathtaking publication quality imagery unrivaled by your competitors but also your ability to nurture and assist in development of other aspiring talent emerging within the industry.

Wishing each and everyone an epic Summer Solstice...

I agree so much! I could NEVER afford the Latest & Greatest in Camera Gear. I cut my teeth on anything I could afford from the Pawn Shop I worked at. [Yashikaflex TLR] I had a Fujica Filim camera and graduated to a BASIC Nikon F4004 starter kit with Qunataray Lenses. When film faded away, I spent the next 20 years using various
[Kodak & Panasonic Lumix] Point & Shoot Digital Cameras. I finally found an affordable D3100 a couple of years ago. Other than my last film cameras, NONE of this equipment is less than 10 years old.
So, ALL of my Digital Immages have been taken by Legacy Camera Equipment, & I have adjusted to the limitations of my equipment and STILL enjoy my hobby.