Whilst no decision has been made it seems as though the F35B is the only game in town, for the RN in particular.
It's rather worrying though looking at the potential costs. Project is only slightly behind schedule but costs seem to be rising exponentially. The US will be paying an average of over $100 million for theirs, and the B is significantly more expensive. Initial B examples are looking at close to double that. PW seems to be running a campaign to get the F136 canned as well, the DoD hasn't requested funding for it in the last couple of years.
Oddly F35As were offered to Norway for about $60 million apiece, though the price offered wasn't a binding contract.
Does anyone think our defence budget can afford $120 million dollar airframes?