As the RAND report correctly notes, Turkey is at a turning point:

The real threat confronting the AKP at the onset of Prime Minister
Erdoğan’s second term is not a direct intervention by the military, but
rather a decision by the judiciary to close down the party.
..and very likely to turn in the wrong direction, with the secular-Atatürkist "deep state" apparatus banning the party and its key leaders. Given the AKP's relatively impressive record of governance (better than any other Turkish party in decades, I would argue), and its very moderate and democratic Islamism, this is indeed a depressing possibility.

It also has broader implications: radical Islamist movements are likely to point to the AKP's fate as proof that electoral participation and moderation are pointless. Even when you win elections, increase your vote share in subsequent elections, promote foreign investment, improve human rights, participate in NATO (and send forces to ISAF), try to join the EU, and mediate Israeli-Syrian peace.... you still aren't allowed to stay in power. Why not then turn to violence?

I've yet to hear Western governments weigh in on this in any significant way. Certainly, EU leverage has declined as EU accession looks increasingly unlikely. It is also hard for outsiders to comment on internal Turkish judicial processes without raising nationalist hackles. Still, it would be a tragedy if the remarkable democratic transition in Turkey was reversed.