Don't get your hopes up because all I am reading here is confirmation that FM4 will have the same ALMS integration as FM3, only now they get to put an ALMS logo on the outside of the box.
They claim 26 cars, yet their gallery shows cars not racing in the series anymore. They haven't said every track, and only listed 4.
Until I see otherwise I am not expecting anything other than cars and tracks included in the game with perhaps some career mode races based on real life races.
Both these links are showing images of older cars. Andretti Green is not in the series this year and those Acuras are LMP2, which only participated in a handful of races early in the season, and neither of the Acuras pictured were in those races. I need to check FM3, but I think the Aston Martin Muscle Milk car is the only new car we have seen.
I hate to be all negative on this because I want an ALMS game, but I feel like this will be just like FM3 where the new cars from the current season will be DLC. I have not seen evidence to the contrary.