Well, he's really only talking out loud and soliciting feedback from his fans on what his company should do, but I personally think that being part of Phase One is something only his bean counters can answer, but failing to support 4E would be disastrous.
First, I don't care what's out at launch. I'll need time to digest the new rules, and I won't be buying any supplements out of the gate except for maybe a WotC adventure to see how they're doing things. I don't usually buy non-WotC supplements unless they suit a specific need of mine for a campaign, are award-winning, or are totally new and badass. None of those three are likely with a new rules system right at launch. From what I understand, a lot of the gaming population is this way, even if they are willing to purchase third party products. So the Phase One participation is a moot point unless they think they can make money off of it.
As to their existing product line, I don't think it can stand on its own in the absence of D&D.
M&M is like what Winston Churchill said about Democracy. "[It's] the worst form of government except for all those others that have been tried." It's not hopelessly complicated like Hero, and the overall feel of the system is better than GURPS (which, IMO, has some bizarre artifacts related to its generic, universal nature). It could ultimately stand as a core product, but I don't think it's there yet. It seems servicable as a supers system, but it doesn't make me WANT to run a supers game just because I've read it. The rules aren't elegant enough yet, especially where they interlock their own ideas with the d20 system.
True20 I can't really speak for because it's not different enough from D&D to interest me, and shares enough of the flaws of 3E not to stand out for its rules changes. YMMV. But, the Ice and Fire book, I think, depends a lot on 4E. I'm a huge Martin fan, but none of my group is. Unless there are good rules I can steal there for a 4E game or some homebrew game in an Iron Heroes vein, I won't be buying.
Ultimately, I think a lot of people seem to be a lot more surprised by the license changes than they should be. Everyone seems to want them to fix the d20 glut problem first, and second... they don't owe anyone the right to use their products to make money. When you make your money based off of another company's product, things like this can happen.
Further, while it was necessary to have a mechanism to allow fans to show their house rules off, and for other companies to support D&D, I don't think that games that don't require the PHB, suchs as M&M, True20, Iron Heroes, etc do anything other than cannibalize audience from WotC's products. How many people are talking about sticking with True20 over 4E? Anecdotally, I know myself I stopped buying D&D books for a good year because I was running an Iron Heroes campaign. I think it makes good financial sense for them to tighten up the license, because the old one was too lax.
