Has "midi" been replaced with something better?

Answer 1

MIDI is still being used all the time - MIDI is just the language in which a piece of digital gear (like a keyboard) can "talk" to a computer.

It's the sound samples that have gotten better - there are a lot of products on the market that are so good they might be mistaken for real instruments, even to professional musicians. (check out this drum program, for example:
http://www.zzounds.com/item--FXPBFD

Answer 2

wav and polytonics