As I have understood it, Honda never likes to fiddle around with "concept" versions of the Accord, so even having one show up in Detroit was a HUGE step forward for the company. From what I have heard and read, the next-generation Accord is in the same time-frame as most new cars this year, sometime in the fall for a debut, probably on-sale by the end of the year.
The big question is whether or not Honda will decide to combine the Accord back to the way it should be, without the Accord Euro/TSX and "regular" Accord. The problem is, the new Camry and the like is rather large, and I doubt a full-size Accord would go over well in Europe, so, probably not. We Americans and Aussies thereby would expect a large model once again.
As for engines, I wouldn't doubt seeing much of a departure, if at all, from the current lineup of I4s and V6s. Chances are that a six-speed automatic will be added to the mix, and of course there will probably be a diesel model available as well.
...After all is said and done, Honda has a pretty large uphill battle to fight. Granted of course that the current Accord, despite its age, is probably the best mid-size car you can buy in America, that doesn't mean that cars like the Malibu/Aura, Altima, and yes even the Camry would give it a run for the money. But even beyond that, the new Camry is rather dismal, the Altima caters to the young and vibrant, and the Malibu/Aura while good cars, probably won't match-up to an all-new Accord.
That said, I think we should be more worried about that FoMoCo plans to do with the next Mazda 6 against the growing sea of competitors. That will indeed be a make it or break it car as well.