The US is not going to switch to proportional representation at any point in the near to medium future. It's just not going to happen. There's zero public awareness or desire -- right now we're having a hard enough time just making the much smaller incremental improvement of ranked voting.
On the other hand, there's no strong tradition of any kind behind drawing districts. If someone really can come up with a fair, objective way of doing it, it's far easier to see it getting adopted. Gradually at first (state by state), and then possibly nationally. Still difficult, but within the realm of possibility (unlike PR).