Its a nice idea isn’t it;
1) Spain accepts that democracy must rule.
2) Catalans vote for independence.
3) Catalans stay in the EU or not (it’s their choice)
4) Catalans stay with the Euro or not (same as above)
5) Catalans walk away from their share of the national debt and start from scratch.
6) Investment rushes into Catalonia. (to “support” them, not to fleece them of course)
7) Spain continues to function normally even with the increased debt burden.
8) No bloodshed on the streets.
9) Everybody sings Kumbayah.
The only point I’m interest in the first point, the rest is speculation.