> I'm not sure if there are physical limitations preventing a room temp superconductor.
Not really. We just know that it’s very uncommon at best. The limit is material dependent and we already have superconductors with more than one order of magnitude difference in their critical temperature (e.g. ~4 K vs ~40 K; YBCO, which is widely studied, is at 90 K). It is not inconceivable that we could come up with some fancy material with a critical temperature three times as high again. There are several laboratories with good money working on it.
Not really. We just know that it’s very uncommon at best. The limit is material dependent and we already have superconductors with more than one order of magnitude difference in their critical temperature (e.g. ~4 K vs ~40 K; YBCO, which is widely studied, is at 90 K). It is not inconceivable that we could come up with some fancy material with a critical temperature three times as high again. There are several laboratories with good money working on it.