A thesis: Sun should be prepared to give up on SPARC
One of the things that Sun is notable for is for basically being the last general computer vendor standing with a non-x86 architecture. Without getting into the debate about the SPARC architecture's long and somewhat questionable history, I think that Sun now really needs to be prepared to give up on SPARC.
First, let's admit something. In general, SPARC is on its last legs, as it has already lost out on performance and general desirability. Pretty much the only market that purchases ordinary SPARC hardware is the legacy customer market.
However, Sun can't just give up on SPARC now, because right now it needs the Niagara SPARCs for its overall 'cool computing' agenda. Sun has to have a power efficient CPU in order to deliver the significant advantages necessary to effectively push forward on cool computing, and the x86 vendors aren't making CPUs that are good enough. Ergo, Sun has to make one itself, and in fact its ability to do so gives it a unique competitive advantage.
The long term problem is that this SPARC advantage is almost certainly dead the moment that Intel decides it needs to seriously chase 'cool computing'. Intel has already buried one competitor that tried to compete on cool CPUs, namely Transmeta, so it can almost certainly do so again if it wants to. So if Sun succeeds in making cool computing a mainline server issue that matters, Intel will have a big motive for chasing the market and will probably squash SPARC's advantages relatively flat. At that point the smart thing to do is to give up on SPARC; trying to compete with Intel is a losing game that Sun has already played once before.
Thus Sun needs to be viewing SPARC not as an end to itself but as a means to an end, a means that Sun is fully prepared to give up on once the end is achieved. Believing otherwise is just asking for Sun's late 90s and early 00s history to repeat itself again.