The federation mechanism that will win will be the one that forgejo/gitea supports first.

Everybody is moving either to codeberg or more likely forgejo instance.

Forgejo already supports ActivityPub, albeit only for a minor use case (starring repos), so according to your definition, it's decided already.

	▲	omnimus a day ago \| parent [-]
		I don't think thats so clear. The forges could support multiple federation systems and if for example someone made quality PR for the ATproto version that could get meged and adopted.