Well yes i would imagine that the ability focus feat will remain or at least some equivelent will exist, but from reading S&P27 it seemed to suggest that abilities now won't have to be bought seperately. I suppose ability focus might cover it, after all a guy whose more likely to suceed on the telepathy check would be scarier then the guy who isn't though in the old edition the differance wasn't staggering.
One thing they might do is allow everyone to use the basic abilities of every power but say that only those who have bought the power can use variant abilities associated with that power (as seen in the psi corp book) attack probes could fall into that category as a varient of pain or nerve stimulation.