As long as there's a less-than-1-year dev cycle, unless they greatly invest a lot of money in expanding the dev team the quality of at least some modes will suffer. Hell, even throwing money at a bunch of new devs wouldn't do much soon anyway as I can't imagine how long it would take new hires to get their head around the game's code base.
The game could probably do with a new engine at this point as it's just been stuff stuck on top of old legacy stuff year after year, but no point from a business point of view if people are throwing more money at them than ever...