As a casual raider it was always quite a perk to have my druid ready for anything. Need a tank, fine, need a healer, I can do that, need a DPS, oh I can do that too. I was a little worried when Cataclysm promised further division of bears and cats, but thankfully it never really came to pass. Perhaps the same will happen this time as well.
My current druid speccing algorithm creates two specs, one focused on tanking while also maximizing DPS effectiveness when possible and a second focused entirely on healing. Now worst case scenario MoP will leave some critical cat ability out of the bear spec like shred or mangle. Best case scenario is that they just leave out some of the quality of life cat talents like king of the jungle from the bear spec. I do have one point in king of the jungle right now, and it certainly helps my DPS, but I wouldn't be crippled without it. Other cat friendly talents like stampede or blood in the water I already do without.
Now a blue response explicitly stated when the topic of off-tank DPS was brought up that no other tanks could do it and that druid would no longer be special little snowflakes. I take that to mean that they will be doing something to completely gimp cat DPS in the new bear spec, but I can't imagine what. Maybe it will just be equivalent to DPSing in a "bear spec" now and blues think that is enough. That's certainly not going to dissuade bearcats from speccing bear and keeping a DPS set on hand.
If you look at the talent trees right now there is a ton of overlap between cat and bear talents where the talent does something that is good for a cat and something that is good for a bear or something that is good for both. A truly sadistic developer could tease those all apart and work all the bear stuff into the bear spec while omitting the cat stuff.
I'm not sure that is likely since it was mentioned they were rolling the talents into the baseline abilities. So long as the bearspec retains all the crucial cat baseline abilities then there is nothing to worry about. Can a bear spec live without shred? Probably. It's not really all that important for soloing when you can't be behind your target anyway. Could they award the cat version of mangle to cats and the bear version to bears? That would hinder the bear spec's ability to solo.
So many possibilities, but when does it come to the point where being gimped x% dps isn't worth the ability to heal. I honestly don't heal often on my druid. I did heal a random heroic last night since healers were eligible for the bonus sack, but I can't remember the last time I healed before that. In the past healing has got me into many an informal raid for achievements, gear and amusement. Opportunities that wouldn't have been available if I just stuck to my strengths of dpsing and tanking. Not to say that I'm not proficient at druid healing, I'm actually quite good at it. I just like healing on my shaman more.
One thing is for sure, a cat spec won't be able to seriously tank without the crit immunity and extra mitigation that will undoubtedly be thrown into the bear spec. So the bearcat lifestyle rests squarely on the bear spec. Trispec anyone?