Hello, and welcome to the Tor community forum!
I just answered a similar question over on r/tor on Reddit. Going to copy and paste my answer here. The short answer is yes, we will eventually be moving to a hybrid encryption scheme for post-quantum encryption. We have a significant dependency we need to fix and deploy in the network before we can do so, though, and that’s “fragmented cells.”
Fragmented cells will allow us to split messages over multiple cells within the Tor network, thus opening us up to having much larger handshake material passed around amongst relays and clients. This is needed since most of the post-quantum handshakes bring significantly larger payloads with them. The most up-to-date specification for fragmented cells can be seen at proposals/340-packed-and-fragmented.md · main · The Tor Project / Core / Tor Specifications · GitLab
We plan on rolling out fragmented cells later this year as we begin the work on supporting UDP within the Tor network as well.
Once fragmented cells are in, we can begin the development of circuit-level post-quantum cryptography. For the outer TLS layer, we will likely need support in the commonly used TLS libraries deployed in the Tor network (OpenSSL, LibreSSL, etc.).