As long as Apple satisfactorily supports existing Power users and it is economically feasible then they should support Power in 10.6. It would be no different than Apple supporting the last Intel boxes when the next big thing comes down the line. If Apple drops Power support totally in 10.6 then that's prerogative. I won't like it but Apple will do whatever makes Apple money. Apple is not in the charity business.
I am all for technology and progress. If Intel, AMD, IBM or whoever comes up with a better architecture in a few years then I will go for it.
Perhaps for Mac OS-VI we'll see Apple dumping Intel in favor of the next new kid on the block?