Well lets assume this story is true. What is implied? If Sun went to the Opteron for it's workstations and high end servers it would abandon it's SPARC processor. The SPARC unlike Intel and even poor MIPS doesn't ship a lot of units. That keeps Suns costs' high. They have to divide the cost of each chip generations development over the total number of units of those chips they will sell. Which is very, very small compared to any Intel or AMD chip. Tens of thousands, not millions or tens of millions.
What OS would these boxes run? One assumes Solaris, which has been ported to Intel for years but which lately Sun seemed to have lost interest in. Or perhaps Linux which Sun has lately been more interested in.
It's hard for me to imagine that Sun would go from a proprietary chip and OS to being a Intel/Linux box maufacturer .. leaving behind it's entire legacy.
Perhaps these will simply replace the intel chips in the Cobalt rack server divisions products? That seems more likely.