Best case scenario, Trump is deposed and he is forced to tell the truth, which is that Obama didn't wiretap him. If Trump lies, then he must be impeached for high crimes and misdemeanors. According to the Republicans in 1999, lying under oath qualifies as "high crimes and misdemeanors."

I wouldn't get my hopes up though because the Republicans control the house and the senate. They value party over country so until they think that Trump is a detriment to the party, they're not gonna do jack shit.