Hasbro definitely did make money from the d20 licenses: The license made sure that D&D3e was required to play any d20-licensed product (and that this was made very clear on the product covers), and I suspect a lot of D&D core books were sold for use with other products.
OGL is another matter, as this allows complete games to be made. But d20 products outnumbered OGL products by far, so the overall effect was still good revenue for WotC/Hasbro.
I think there's something you're missing in your analysis. When DD3 came the intention was to renovate an ageing product that was going down the line. The idea was not only to bring back old consumers but also to bring in a new generation of consumers. And the idea was also to make them long term consumers that would keep buying stuff. I'm sure that WotC/Hasbro didn't want just a short term bubble. Now, this had to be done fast and for that purpose they needed to have a lot of varied stuff in the market. Needless to say, that's something they could not do alone.
The move was highly successful since it lead to a renovated and rejuvenated DD/d20 market. But things changed afterwards (and it may be they were expecting things to change). The renovated market for d20 matured. Given the nature of roleplaying, it is not easy to suppose that the trick can be repeated at this stage. There are limits to how often one can renovate a market for products like DD or rpgs. It just can't be done every five or even 10 years. Yes, they have to keep atracting the youg crowd but that has to be done continuously, not in a big bang way has they did with DD3. Where DD3 was a departure from a dying past, DD4 is an evolution in a very lively present.
So from the perspective of WotC/Hasbro I suppose that what makes sense is to consolidate. From this point of view it makes all sense to grab the long term customers created with DD3. Why should these customers be selling to other companies instead of them? They may expect these customers to move to DD4 and they prefer to have them buying their stuff instead of another company's stuff. Killing the OGL is the best way to ensure this.
Purely from an intuitive perspective, I woul think that any new or updated OGL's and D20 Licenses will be very changed but not disapear. No company, no matter how large, could or would want to produce all the possible material that could be produced for a single system.
However, this can be a good thing. No one wants another bubble to pop under them and everyone is a little leary of going into the market the same way they did before. I don't have high hopes for 4e but I do look forward to seeing what develops.
My thought is that there will be something like the D20 license.
WotC can't afford to produce the same wealth of support material - and even if they could I doubt they would make the sort of profits Hasbro would expect, if they were even profitable. I may be wrong but I would need real evidence to convince me that WotC took a net loss from the D20 program.
On the other hand, if their main business is selling core books then they need revamps as part of their business model - to sell extra copies and to justify the existence of a significant RPG division. The arrival of 4e is at least consistent with that.
OGL is more doubtful. I don't see that there is much return from it - and in fact by creating competitors it may even hurt sales a little. I wouldn't be surprised if WotC release the 4e SRD under a new, more restrictive, license.
My best guess is that WotC are writing their new licenses and they're behind schedule - as they were with the originals.
I'd say that if you're not right on the money, you're darn close.
IF Hasbro releases an OGL for D&D4, and that's a big if, it will be a shadow of it's former self.
Ironically this entire situation reminds me of the Windows Vista situation. Without the external support that Hasbro and Wizards got for 3rd ed. 4th is not going to be anywhere near as well off. It will spike for the short term and then tank.