Depends on the instance. Some instances will enshittify, others will fight against this sort of thing. Since Lemmy is federated, if we're stuck on the former we can move to the latter without losing access to the entire network.
You canā€™t fight against it. Thatā€™s the point. The only tactic is to stay stealth as long as possible.
You wonā€™t win with barrage of AI generated content and massive corporate machine of marketing. No filters or countermeasures are enough against the brute force of money. Not to mention Lemmy is relatively easy to spam and troll compared to Reddit if someone wants to do it.
Itā€™s vulnerable by design because the same vulnerability is a feature of freedom of speech and openness when there are no bad actors.
Itā€™s kind of like anarchism if you think about it. Great concept but collapses from miserable human condition.
I predict we will all(technical hyperliterates) be on some form of TOR sooner or later because thatā€™s the only place where advertisers and ai wonā€™t dare to go.
You can fight against it, but it's an uphill battle. The most likely responses to work will be invite only systems for account creation (something I've seen predicted happening to art communities to filter out AI garbage) and some kind of reputation/report system to weed out spammers and the accounts that invited them.