That’s a good question. I don’t think it requires a majority of notes, but I do think it requires a large consensus. Maybe larger than it has now?
Re: a soft fork, I have posted a question on Matthew Kratter's videos: if we only have 20% of node runners switching to knots why do you think we have sufficient consensus to force the miners to mine the soft fork blocks?
https://fountain.fm/episode/WOslYaeXHkGPni8BznUK
nostr:nevent1qvzqqqpxquqzp2zlqylc5unn2p8n4k9y2mt870nv5hl2s2j6e5rup8ewu65205hxv9azaq
Discussion
I don't know what the percentage is. But it seems to me that if 80% of nodes will accept non-BIP444 blocks then why would miners care about the 20% of nodes that reject those blocks?