Our AAA affiliate for the Padres just booked town for Escondido. They're predicting no minor league affiliates in the area for at least another decade. We can't even support a minor league team, there's no chance at all we will get consideration from MLB. The only shot we ever had was the Expos, and that was a real small chance.
As far as NFL goes, this is basically an extension of the Seahawks market. Even though the Portland market itself is bigger than about half of the markets that have NFL franchises (significantly larger than some) we're not going to get one. This is good for the Seahawks franchise, though, as it effectively gives them among the largest markets in the league.
This is all for a number of reasons, Portland city government being a big one. Refusal to get rid of the Memorial Coliseum is another. We only got an MLS franchise because, as best as I can tell, we're trying to be more "cultured." Our city council opted to spend more than a billion on things like bike lanes, aerial trams and fareless street car expansion but couldn't come up with literally a couple dozen grand to keep AAA ball in town.
The only plausible idea we've got, which has never been discussed meaningfully, is NHL. We have a moderately successful WHL franchise (think independent farm league for NHL), and there's currently a 1,000 mile vacuum between Vancouver and San Jose. But I doubt the NHL is going to be in a position to expand any time in the near future, especially as long as they remain on Versus.