Big projects get delayed, and it is not unique to videogames (public work projects seem to have the worst time of it). My experience has been that schedules are picked assuming some level of resources, but other issues crop up on other projects leading to slightly fewer warm bodies than expected on the bigger item. Overt optimism can also be a pitfall, but that seems pretty rare with experienced people who know what they are aiming for.
Anyway - schedule items that are short term (or for videogames you are not a investor in or developer on) are not worth being worried about. I'm sure you'll get to play the sequels for those games (and maybe a couple clones) 1.5 year from now.