No it would not. Milwaukee would still be the smallest in MLB. The biggest market without a MLB team is actually Orlando. Charlotte is also higher than Portland according to Nielsen.
The Milwaukee size markets are Cincinnati, Las Vegas and Jacksonville so you got one right. Salt Lake City and San Antonio are closer to San Diego and Portland than they are to Milwaukee. Milwaukee is at 900 households and Nashville is at 1,169 and Portland is at 1,293. Las Vegas is closer to Milwaukee at 870 households.
Portland has also been losing population at the sixth fastest rate in the US. If that continues Portland will be closer to Milwaukee media market wise and if Nashville's population continues to grow it will be closer to Cleveland or Sacramento which both sit around 1,500 households.