I've been gaming in WotC's D&D longer now than I played in TSR's game (which was only a little more than a decade for me). The d20 system (and its derivatives) are definitely my base for tabletop RPGs (despite playing many other systems, just not as long term or frequently).If D&D died when 3e came out, I guess I've never actually played D&D. It's changed greatly, from what I've heard, but it feels very much alive to me and the millions of current D&D 5e players around the world.
I don't mean to imply that people who play more modern versions of the game aren't playing a version of D&D or that it's not legitimate. I'm just curious if there is enough of the core game remaining that the current edition is identifiable to the original design and feel of the game.
An analogy might be from the video game industry. Could you be someone who played Atari 2600 back in the early 1980s - say a shooter like Centipede - then pick up a modern PS4 controller to play Call of Duty (or whatever)? Both are video games and might be fun experiences, but they are very dissimilar.