The 6502 was a good architecture for it's time, but now times have changed.
Modern processors are designed for executing high-level language code, specifically C like languages. There's a lot of code out there now that you wouldn't want to throw away, so any worthwhile modern processor will most likely run compiled C like code. If that is the case then the character of the processor is not really important.
The 6502 was designed when memory was faster than processors, so many decisions were made because of this. Today it is the opposite and that is why we have caches and large register files. So a modern processor would need these too, further moving it away from the character of the 6502.
Direct page is hard to work with in a multitasking operating system, so it's benefits largely disappear.
It is interesting to look at the x86 architecture evolution as this gives us an example of a 70's design that has evolved. In the end though I'd think that very little of the character of the 8080 or 8088 still exists in the modern chips.
As a hobby CPU though we could look at it differently. What could be done to increase the performance of the 6502 to a level that it could be more useful, while still being a 6502. That is probably a more interesting question. The 65C816 takes one step in that direction, but it's interesting to see that it does not get all that much attention compared to the 65C02, many people prefer the nostalgia of using an original 6502 to the benefits of the 65C816. In my opinion I think that the 65C816 is a more interesting chip to use today than older 6502's. It definitely has some advantages for targeting high level languages. One interesting thing when implementing a compiler for the 65C816 is that there is almost no need for register allocation algorithms (because there's basically no registers
), and that makes a compiler easier to implement.