Ah, what the hell.. you know what? I'll play. Note these are uneducated guesses by someone who is NOT in the know, and these guesses are not to be taken as any kind of reasonable guess as to what the MAME team will or won't do, nor should it be taken as prodding in the general direction of anyone on the staff.
That said, here're my semi-sane predictions for 2011 and MAME:
1. More improvements on discrete audio, especially on the early Nintendo stuff, as MAME edges in ever closer towards perfection.
2. At least one laserdisc title being added, with cackling from assorted MAMEdevs when someone complains about the HD space consumption.
3. There will be no major work done on Model 3, 720, racing shifters, or other projects where people show a habit of all but verbally assaulting MAMEdevs.
4. A certain cheat system still remains on the fringes of sanity.
Here's something a little more out there:
5. Decoupling of the MAMEUI front-end from the emulator backend in order to make maintenance easier in the long term.
Here's the wacky stuff:
6. I predict one slightly newer CAVE title makes it into MAME at a completely unplayable speed due to system requirements. Complaining ensues to the point the forums here are choked.
7. Aaron Giles is promoted to take over the Microsoft Game Room project (with the current owner out of business, MS would have to take it over in order to see it succeed even partially). His leadership skills cause a complete revival of the project, making him a leading candidate for US president for the next election.
8. Konami stops ripping us off on the Castlevania: Harmony of Despair DLC, if only because they'll have run out by next year.. okay, not technically MAME-related, but it's still on my mind.
Okay, that.. about covers it. A good chunk of that is tongue-in-cheek, but we'll see where things stand in a year.