Not even remotely, even if Mobile Linux was good and viable the grand majority of disgruntled Android users aren't switching. Thats if it was good and viable which it isnt even remotely. Hardware support is poor, the software experience is extremely bad (yes I have actually used postmarketos), and overall its just not something that people are gonna want to use.

On September 30th when people look for alternatives they will find nothing and give up, if there was a viable alternative google wouldn't be doing this