There seems to be a large amount of labour voters turning to plaid, at least on the regional list. I can see plaid improving on their seats last time and it’s a win win for them.
As long as Plaid maintain or improve seats and number of votes which does look likely, if the Tories do well and weaken Labours stance considerably on last time then Plaids negotiation power increases with every seat that labour loses.
In regards to the independence debate a lot of Labour supporters are at least considering it now and an 825% increase in paying YesCymru members (in less than 12 months) show there is an increased appetite. The seats to watch are the pro-Indy labour candidates, if they win their seats in addition to Plaid winning seats they could make up a solid portion of the Senedd.