In my previous post, I described exactly how inter-grid content creators are going to become walled out of Second Life. But the Second Life® Terms of Service and third-party viewer policies will also bite third-party developers, hard.
In particular, the ToS and third-party policies place restrictions on GPL usage and distribution for viewers that connect to Second Life, as I've blogged about it before. Also, Section 2(b) of the third-party viewer policy will affect the major third-party viewers(Emerald, Meerkat, Imprudence etc) because they all have content export capability. If a third-party viewer developer wants their viewer to comply with the policies, then they will have to somewhat cripple that functionality(no full perm export, creator-only), despite legitimate use cases that warrant it.
A third-party viewer developer now has this hard choice to make: either cripple certain functionality and accept restrictions on usage and distribution, or rewrite their viewer as "not for Second Life use" and as a result lose much of their current user base in Second Life.
From the discussion going on in the opensource-dev mailing list, it seems virtually all third-party developers are going to take up the latter choice. But that may wind up to Linden Lab's disadvantage in the long run, because that means those viewers' innovations will be re-geared to benefit Second Life's biggest competitor: OpenSim-based grids.