Elisir: TBA (as Dulcamara) is now Erwin Schrott for the January/February run. Interesting, though I suspect Maestri will be the more humane option.
Trovatore: TBA (as Manrico) is now Welsh tenor Gwyn Hughes Jones for the fall run. More significantly, Sondra Radvanovsky is now too busy with Ballo (see below) to sing Leonora mid-October, and we will instead see the debut of Chinese soprano Guanqun Yu, a second-prize winner in this summer's Operalia competition.
Otello: In perhaps the biggest announced improvement, Placido Domingo's semi-pro conducting will no longer mar the March run, with Alain Altinoglu instead on the podium. The March cast (Cura, Stoyanova, and Hampson) is still rather curious -- and a less sure bet than the fall lineup (Botha, Fleming, and Struckmann -- the former two fantastic together in 2008) -- but it will now at least be worth sampling.
Ballo: Karita Mattila is out as Amelia and Sondra Radvanovsky in. Doesn't take much luster off this particular show, but now the Met will have an entire season without Mattila. Radvanovsky and Hvorostovsky have made magic before in this music, though I expect their tenor co-star Alvarez to be more professional and admirable than electrifying.
Don Carlo: Not quite sure why (it's two months after the final Ballo), but Radvanovsky is also out as Elisabetta here, with Barbara Frittoli as the replacement. I'm not sure why she's still considered a star, but Frittoli is usually quite committed despite up-and-down vocalism. In any case, the male lineup here (Vargas, Hvorostovsky, Furlanetto, and Halfvarson) are still remarkable, though the production is not.
Quick classifications, in basic priority order both overall and within each category...
Yes!... if the production doesn't bomb
Sure to please
Figaro / Don Giovanni (it's the season of Abdrazakov)
Carmen (don't miss Lee)
Could really be something
Troyens (Graham for sure; who knows about Voigt and Giordani?)
Only if you like that sort of thing
Francesca da Rimini (Italian late-Romantic melodrama)
Rigoletto (winter) (excellent singing + off-target acting)
Giulio Cesare (David Daniels, or you really like Dessay)
Rondine (rolling the dice on the lead soprano)
Turandot (rolling the dice on lead tenors)
Barber (kids' version)
No, just no