Our network protocol itself supports IPv6 fully, in fact my satellite in the past ran with full Dual Stack.
As you correctly mentioned, we are currently relying on Google GCP for our satellites which do not / or just partially support IPv6.
Besides that as mentioned from other answers above it is not “just a switch”. It involves lots more than just adding an IPv6 address to the satellite/storagenode (eg. equal chances for nodes regardless of the protocol, making sure IPv4 only clients can sill upload, not getting just IPv6 only nodes returned for it)
All this said, i can give you a little of an light at the end of the tunnel. I am working on exactly this at the moment, trying to fix more fine grained details such as keeping track and returning both IPs to clients/storagenodes, managing audit/repair problems if any of the two IPs advertised by a node is not reachable properly, etc.
EDIT: I also know, that more and more ISPs stop handing out IPv4 for free, but hoping IPv6 will solve the problem is also a little foolish to believe in. Many, many, many companies are not using/supporting IPv6 in their network thus drastically reducing the amount of traffic you might receive when only serving via IPv6. As mentioned before, it is not “just enable” or “just switch”. 