Ride systems don't mean anything in regards to capacity. Dispatch intervals do though...
Does anyone HONESTLY think that Frozen's capacity will have any affect on the queue times? Can someone tell me, with a straight face, that Frozen wouldn't have a 150 minute queue even if they doubled or tripled the capacity? It's going to be a 2-3-4 hour queue regardless of the capacity. If guests are going to pitch a fit over a 150 minute queue, who cares what the capacity is going to be- it's still going to be a 150 minute queue. Frozen is going to accommodate most guests per day than Toy Story Mania will even after they expand it. Radiator Springs Racers still has a huge line years later and it's got decent capacity.
Besides, if Frozen truly is a "passing fad" like so many Disney fans desperately want to occur (for some insane reason), then perhaps the ride doesn't need a massive capacity.
Little Mermaid is an overbuilt elaborate queue for a C/D ticket Fantasyland dark ride that has monster capacity, so the queue times fluctuate between short and reasonable. Because of that, some say that Disney wasted too much money on the queue/facades/capacity comparative to the sort of ride it is. Since Frozen is intended to be in the same vein as Mermaid in terms of quality (thought projections are going to be amazing), then I guess those people are going to get their wish.
Seriously, I'd bet that "Maelstrom: Featuring Olaf from Frozen" and a single static Olaf character at the end would garner a 4 hour queue.