It seems like, in the mass of debating which method of healing requires more "skill" to play, we have totally missed the fact that BOTH methods are usually required to keep the tank alive.
It has been mentioned, priests are the MOST diverse healers. Therefore the most
SKILLED priests, play to compliment the other healers in the raid at any given point, not decide their play style and stick to it.
You got Paladins spamming big heals on the tanks, or another priest stopcasting? Downrank. You have a paladin/druid/shaman spamming low ranks/small heals on the tanks? Use stopcasting. There are plenty of ways to take into consideration the raid make-up and decide what your playstyle should be for any given fight. The priests that adapt on a whim most effectively are the priests with skill, period.
With the removal of downranking, its going to make healer composition and assignments a bit more challenging but give priests more limited options on their playstyle.
To answer to OP, yes I believe priests will still be a fun healing class, though from the sounds of changes made to other classes they may be fun as well!