First off, an RPG doesn't
need a big online component, 3rd party publishers, or even to win over every single player who is satisfied with an earlier edition. Even if there was no GSL or DnDInsider at all we'd still have D&D and it will live. The fact that we do/will have these things can only make it bigger.
Second, I'd hesitate to write off Gleemax and DnDInsider because they haven't even been properly launched yet. All we've had so far are alpha versions and early beta. If you can gauge the death of D&D from such things you must be some kind of prophet who can also do it by the stars and the entrails of boars.
Third, I doubt Paizo is a big blow against wizards. I have several reasons for doing so;
* Pathfinder mainly appeals to people who have found their ideal game in 3.x, and so these people weren't a good market for 4e to begin with.
* All of Pathfinder so far is alpha and freely available for all. Pathfinder so far does nothing but bleed money for art, salaries, and god knows what else without making any real bucks. When the time comes for Pathfinder to get a true profitable release, 4e is already out and established with plenty of time to win over those who are sitting on the fence or even those who'll cave in to peer pressure and the desire to play the Next Big Thing with a real book.
* I personally suspect the final release will be 95% similar to the latest free beta, providing little incentive to buy it.
* I also think the backward compatibility of Pathfinder will seriously suffer and has indeed already done so. The exact level of compatibility will swing around like a yo-yo as more changes get introduced or removed, which usually won't exactly build a lot of trust and faith with the fanbase. In the end people will stitch together a Frankenstein's monster out of 3.5, 4e, and all various versions of Pathfinder there are to create their own homebrews. In short, I expect that Pathfinder makes a grab for the fragmented sector of the market in a hope to bind them to itself only to end up pulverizing shards into dust.
I consulted the tarot cards and the flights of migrating birds to back me up on this.