I feel like losing TX would actually be a huge blow to the GOP whereas AZ/GA/CO/VA drifting away from the GOP are just cuts they can still make up for. Right now, I don't think the GOP has any sort of realistic electoral path without Texas (assuming Dems also carry GA and AZ), which would really force the party to do some soul searching.
I feel like we're too polarized for a party to be locked out of the electoral college like that, I think that if the Democrats are consistently winning Texas, they're making up ground elsewhere.