Well, the general discussions in several places seems to target away from Mastodon due to their way of implementing ActivityPub, companies and/or organizations can however make own versions and soon they might implement new functions that is not mentioned in the specs.
This was more or less done with xmmp too. Once there where bridges towards icq, msn, gtalk, etc... They all closed it down. Xmmp still exists but not like people once had
Minds and Nostr are just early signs, it can't be stopped unless we close the specs.