Why wouldn't it die? Brawl killed it when it came out, and Brawl has some major flaws. Smash 4 fixes all those flaws, is currently riding a huge hype train, has the potential to bring in tons of new players, and most of the Brawl and Melee pros that I've seen have said they're going to play it when it comes out. There's going to come a point when CRTs and Melee discs get too scarce and expensive for there to be enough setups at tournaments, when people get tired of seeing Fox and Falcos in almost every match, and when the metagame gets stale because the game's been played for 13 years, regardless of how much people like Smash 4.
There are plenty of reasons Brawl would be better for him to start with than Melee. Smash 4 is much closer to Brawl than Melee. He said he can't play on Dolphin, but Brawl on wifi wouldn't be a problem (assuming he has wifi). He won't need to buy an increasingly expensive Gamecube controller (Wiichuck is a perfectly fine control option, especially since he's never used a Gamecube controller). Brawl is easier to find and probably cheaper than Melee since it's a lot newer.
Are you saying you'd recommend someone to play SSF2 Turbo over USF4? Admittedly I'm not too familiar with Street Fighter, but USF4 is much bigger from what I've seen. I have a feeling Nintendo won't release Melee on VC any time soon since they want to push Smash 4 as much as possible.
Edit: Besides the above reasons, he'll be able to focus more time into fundamentals instead of Melee AT's which won't be in Smash 4, and he'll be able to get used to the buffer which I think is returning.
First, Brawl didn't kill Melee. It did overshadow it for a short time, but Melee is presently the dominant scene by a large margin.
Also, considering he's already used to Super Smash Flash 2, which has a similar end-goal to SSB4, he'd be better off practicing on that if you asked me than Brawl which is objectively far more defensive, something Sakurai is actively trying to cut down on according to a question asked in a letter to him. Again, not trying to bash Brawl, but it'll be more different than you think.
And if you think me recommending a fan game is an insult for any reason, you need to think about the fact that it's my own competitive Smash game of choice, above Melee and P:M. It's not the
better game, but I have my reasons for following it, and I wouldn't if there wasn't some quality and effort in its balance and depth. (And the functioning wi-fi helps.)
And I won't comment on recommending SSFIITurbo over USIV. I strongly recommend it for learning the basics of the series and for fighting games in general, along with still being an enjoyable experience - USIV is overall better, but generally more overwhelming to beginners and ultimately an entirely different animal than the II games. Just like Melee, Brawl, and U/3D are entirely different animals from each other. Experience from one will for the most part not carry over into the next, whether it's from Melee to Brawl, from Brawl to Melee, or from either game to U/3D.
My point is, the scene's not dying anytime soon, so it's there if he wants it. The Brawl and P:M scenes are also there. As is the Super Smash Flash 2 scene. And soon the SSBU/3D scenes. Each is different from each other. You can learn the fundamentals on any one of them.