“Only the candidates that have won a majority of delegates in at least 8 states (GOP Convention Rule 40)”
It is pretty much a given that Rule 40 will not exist by the time the convention is held. There is a rules meeting, I believe 2 weeks before Cleveland; anything can change.
The delegates will vote whether to change the rules. Unless a majority of Trump’s and Cruz’s delegates vote to expand the list of eligible candidates (and why the hell would any of them want to do so), then Rule 40 will stay as it is.