The 6502 is still doing hundreds of millions of units a year, and is still a terrific introductory processor that is comparatively easy to wrap your head around, especially if you are interested in board bring up from scratch. (Compare the requirements to boot a 68000 to a 6502 into a nop loop, for example.)
Indeed, it is highly useful for learning projects. See Ben Eater's "Building a 6502 Computer" series[1], and Quinn Dunki's "Veronica"[2], each a from-the-ground-up creation of a system around the 6502.
Glad to hear it! I first learned assembly for 6502 on the Apple ][, and found it indeed easy to wrap my head around. Great machine, great architecture, TED II Editor/assembler was amazing...
The great thing about the Apple ][ was that it was largely the work of Woz and thus it was very much possible for a single person to fully understand the whole thing. Even the addition of AppleSoft BASIC and DOS didn't keep it from being comprehensible.
There are microcontrollers that you can program on an easy-to-use USB-based development board, that lets you debug C code with a breakpoint debugger. Your program is stored in flash memory on the chip: you can just unplug it, and plug it into your project board.
If you're going to use a microprocessor with external peripherals for everything, I'd just bite the bullet and go for a MC68000.
I have that Microprocessor Systems Design somewhere (Alan Clements), from many years ago. I remember the MC68000 examples circuits and code in it are not too bad.
Here is a possible consideration: the MC68000 has DTACK line with wait states for accommodating slower peripherals. The 6502 is synchronous: it expects peripherals to respond according to its clock, on time.
The 6502 is far from dead.