"While the Mariners successfully co-exist with the Seahawks and Sounders in the adjacent CenturyLink Field, Lincoln notes that an NBA arena will need to host 200 or more events a year to be financially viable and would thus dramatically change the road and parking situation in an already-congested area."
Graph below shows scheduling of hypothetical NBA, NHL, and MLB teams in Seattle. Dates used for NHL are from the Vancouver Canucks in 2010-11, the OKC Ahem in 2010-11, the Seattle Mariners for April 2012 and the Texas Rangers for October 2011 (playoff data for Mariner games is slightly outdated).
Note that in the entire calendar year, there was one date (April 13) where a regular season Mariner game overlapped a regular season NBA game and no cases where a regular season MLB game overlapped a regular season NHL game. Note that there were six instances - in total - where a regular season/post-season MLB game overlapped a regular season/post-season NBA/NHL game.
In other words, in a typical season where the Mariners miss the playoffs and the NBA/NHL teams leave by the second round, we're talking about three or four days a year where a scheduling snafu might arise.
Not exactly 200, but, then, why let the truth get in the way?