It will always be better.
If Apple ever takes a step backward then I'd say they're in trouble
Next gen MBPs will always be better in terms of raw performance. Whether that incremental performance boost is useful depends on what you are using your MBP for.
I think for 13" MBP users the coming upgrade will be more significant because the integrated graphics engine on ivybridge is a big step up and we will likely see a Quadcore 13" MBP.
The 15" and 17" quadcore MBP with their discrete graphics will only see a small boost in performance with IB.
And again, the current MBP are as good as it gets for laptop computers. For myself, I don't think there is anything the new 15" or 17" MBP could offer that would make me want to upgrade. Don't get me wrong, if the new MBPs come out with 15 hour battery life and reduced their current weight by 50% I would be tempted. But USB3, a slight performance boost from IB and a slightly more MBAish form factor is not enough to make me want to upgrade. YMMV
Enjoy your MBP and don't worry about the next upgrade because there will always be a next one,