In the far-fetched scenario that the hypothetical proposition in question even makes it on the ballot, I would be absolutely astonished if it doesn't go down in a historic landslide.
Brexit was supposed to be hypothetical, and when it wasn't (Thanks Cameron), it was supposed to go up in smoke...neither happened.
Enough trump failures, enough far-right agenda advancing at the cost of Californian values, enough polarization in general, enough people not caring jack about the consequences and this could very well gain traction AND pass.
Highly improbable [as in, another attempt by SNP to take Scotland out of the UK is more likely], but not impossible.