Will the Revenant & Assassin get support in books, just in Dragon, or nothing at all once the articles are out - that's the big question. Hopefully they'll at least get support in future Dragon issues when stuff like Power book X or PHb X comes out.
DDI exclusive content leaves a bad taste in my mouth, but I guess it's not significantly different from stuff you could only find in Dragon magazine. That didn't always make me happy, either.
Ah, well.

If they don't get the same amount of support the book races & classes get, as far as new feats/powers go, eventually they'll fall behind to the point where they're completely underpowered. The Tiefling Fighter support from MP is a good example of what I mean - without the support of MP, Tiefling Fighters would still be underpowered compared to, say, an Elven Fighter.I don't think they are likely to get all that much "support", but how much support do they really need? We might get a follow up article or two over the years, but I'd be fine with just the original articles (assuming they're fairly meaty to start with).

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.