Taking thedungeondelver's scenario from the OP one step futher, what if Hasbro decided that WotC just wasn't worth it anymore...?
Well, the OP did ask about the personal reprecussions, and specfically not about the business end of things.
[*]Could you see the D&D rules frozen as is, published in one basic book or as an eternal/final Red Box, and sold under the Hasbro brand with the rest of their games (in Toys-R-Us right next to the other "novelty" games like the Ouija Board)...?
I would expect this to be unlikely. Keeping an item in print costs money, and requires a certain level of sales to maintain. I would not expect a static D&D of that sort to continue to sell well enough to keep in print.
[*]Essentially disband Wizards of the Coast and have a small part of Hasbro themself develop/release small "adventure"/"theme" boxes once or twice a year (like new versions of Trivial Pursuit or Monopoly)...?
D&D is not all that WotC does. D&D does not seem to even be WotC's best-selling line. Disbanding WotC would be killing a lot more than just D&D. So, I'd count this as unlikely, especially given Hasbro's historical reticence to sell off IP.
[*]Limit DDI to the final distilled ruleset, and continue the online service but with no more extra innovation (it just is what it is)...?
Possible, as long as the subscriptions were enough to cover operating and maintenance costs for the service.
[*]End Dragon and Dungeon magazine once and for all...?
If you aren't keeping the D&D game alive, then keeping the magazines alive would be a wombat (waste of money, brains, and time).