Of course RIM are committed to the playbook... Most of the other tablet manufacturers have a day job which actually earns them money: HP can dump their tablet platform because it's pretty irrelevant to them. Samsung and Motorola could similarly walk away without regret.
RIM need a tablet because it's too close to their core business NOT to have a tablet. It should have been easy for them to make a "serious" tablet that hooked into their well established eco-system (don't forget RIM is still massively profitable despite the the bad press). So far they've failed because they tried to make an iPad, not a Blackberry.
If they don't get a tablet which works great with their phones, then people will buy iPads, and then switch to iPhones because they don't like being split across platforms, and there'll be no more RIM. Apple are just waking up to the idea (with iCloud) that your phone and tablet should work TOGETHER. RIM should know this already.
If they get it right, there's a huge market for a Blackberry Tablet (though perhaps not a playbook). If they get it wrong then they have to keep at it until they run out of money.