This would be so nice, but it would not work.
First: They would be filled with overflowing players not liking the megaservers, but not really interested in RP. Just like it happened when Classic launched in 2019.
Secondly: After a short time all these non-RPers would begin begging for transfer off, also leading to the transfer off of players, whole guilds even, of players who should not, same as happened with the free transfer off RP realms in Feb. '22.
The only possible way to do this would be to promise 100 % no transfer off EVER! and install some kind of “RP-police” force-moving anyone not complying with the naming policy and the rest of old RP-realm codex off to the least populated PvP Era cluster 