The Barcelona leaving La Liga talk is all scaremongering bullshit. They say the law forbids teams from other countries in, but that's not true, there's just nothing allowing it, it was beyond comprehension when the laws were written.
100's of laws will need to be written and rewritten if Catalunya actually leave, so rewriting one about football is not going to be a big deal.
La Liga can't afford Barcelona to leave, Real Madrid definitely can't afford it, and they'd probably find Ligue 1 more than prepared to welcome them in like they do Monaco.
Tebas the president is a right wing nut, so he likes to talk up the idea that Barcelona would be ruining themselves, but the truth is La Liga would lose more than half it's value to TV companies, viewers and sponsors overnight.