Novell could already just use a wholly proprietary compiler such as icc, or they could take the current GCC and enhance it with private changes (perhaps which they have bought from someone else) which they do not distribute.
So, your bad scenario is already completely possible. The idea, as I understand it, behind the run-time licensing change it to poison the prospects of a commercial marketplace for proprietary plugins.
I'll be more inclined to believe that such a requirement is not necessary when there no longer exists a market for expensive vendor specific compilers for various embedded systems (TI c64x DSPs, for example).
Vendors who are currently raking in additional development fees licensing compilers would have a much easier time if they just had to build and sell a proprietary backend for GCC... so the incentive to not bother with that particular business model would be substantially reduced with an unrestricted plugin model for GCC.