Doesn't Seattle have like 33,000 or around that?
Yes, Seattle does draw a large crowd while some others draw a small crowd.
However, the same distortions occur in both the NFL and MLB.
The range for MLS this season so far is:
11,974 (Columbus) to 36,932 (Seattle)
NHL last season:
11,059 (New York Islanders) to 21,423 (Chicago)
NBA last season:
13,538 (Indianapolis) to 21,791 (Chicago)
NFL last season:
46,431 (Oakland) to 87,047 (Dallas)
MLB last season:
17,435 (Cleveland) to 46,491 (New York Yankees)
This season, with one game left, Oakland trails at 18,232, and Philadelphia leads at 45,440.
I'd put the MLS as in a better shape than the NHL right now. Not to mention that the expenses of running an MLS team are much cheaper than those of an NHL team, while the two have comparable TV deals (the MLS is getting a new one next season BTW).
As far as Chicago is concerned, using this year's MLB attendance minus the White Sox's game today that is not known yet, and this year's MLS attendance to date:
26 Bears 62,195
9 Cubs 37,258
21 White Sox 24,757
1 Bulls 21,791
1 Blackhawks 21,356
14 Fire 14,137
One may argue that MLS attendance figures are skewed by Seattle, but they are also skewed in the other direction by San Jose, whose stadium can only hold 10.3K, yet they average over 12,000 by selling standing room. Given a regular sized stadium, they might actually be around 18,000, but that's probably a stretch.