Several years ago when I bought a slr, I went with nikon, mainly because their F-mount lenses are mostly compatible back to 1959.

It is a lot of fun to pick up and use nice old glass from garage sales and such. They tend to require manual control, but that is the fun part of taking pictures anyway.

Nah, they'll just make the battery an external MagSafe accessory like the Air.

Software security updates seem to be the limit to phone life, not batteries (the latter of which I've had replaced at Apple stores). Apple still seems to have the longest support for security updates.

user replaceable batteries and blue bubbles are the 2 greatest threats to Apple