I don't think the issue will be that queues will always be bad. I think the issue is how the queues will be in the first month after launch. You might note that almost all posters here mention the intention to try the dps classes even if they don't give up on their tanks. That's going to have an impact.
For me personally I will probably lvl a dps and a healer at the same time. I hate questing as a healer and there are going to be a lot of quests. Realistically I will probably be running dungeons with my FC as well so I suspect I will end up being rather neutral on the effect I have on queues.