
What a load of bull.
1) What's your source for this information? It's not because Apple decided to charge just $29 for SL, that it's different from other point releases. Jaguar, Panther, Tiger, Leopard were all upgrades in license, but installed just fine on a clean system.
2) Support for non-intel is dropped, but most of the hardware from the previous age of Mac is already 4+ years old. Furthermore, there's nothing wrong with running Leopard on this hardware for another year, before finally considering a hardware update.
3) Of course they will stop selling 10.5. But that's really not a problem for intel-machines (starting beginning 2006). Merely PPC users who haven't upgraded to 10.5 yet, might want to do that now.
If you like the OSX experience enough to stick with it. Why not give Safari 4 beta a try? It comes with better integration into OSX and has most of Chrome's features, with biggest miss being the sandboxing. It also uses the Webkit engine for rendering webpages, which is somewhat faster than Firefox's Gecko.
"No problem is so formidable that you can't walk away from it." -- C. Schulz