They might if they’re buying more than the assets (i.e. credibility of the whole sector), but the hole is probably too big for even JPM to take it alone. Maybe the top 4 split it between themselves?

It's definitely possible. assets = liabilities + equity. Well, SVB equity has already been wiped out to zero, so that's money JP Morgan doesn't need to come up with to make the value of the assets (i.e their securities) equal their liabilities (their deposits). It could theoretically be worth it to JPM to buy SVB to (a) in one fell swoop take over the biggest startup-focused financial institution, and (b) calm systemic risk fears.