How do you know there will be a 10.5.9? If there is, it might not even be the final update to Leopard due to no PPC support in Snow Leopard. Apple needs to maintain an OS that some users will be on forever.
If there's not $$$ in it for Apple, they aren't going to maintain squat. They couldn't care less about users that bought a Mac over 3 years ago. They want you to buy a new Mac now and every year for that matter. Have you noticed the latest Macbooks have hardware acceleration even in Leopard for H264 video decoding? My MBP is less than one year old. Why haven't they added support for it? It's because they don't care. Their attitude is if you want the newest features (even when they're simply software support in the OS), then buy the newest hardware from them, even if your computer is less than a year old (e.g. there's no reason the previous generation iPhones cannot capture video (hacked versions do it every day), but Apple limits that feature to ONLY the latest hardware to try and get you to upgrade. It's total BS, but they get away with it). It's that TIE between the OS and the hardware that keeps them making record profits even in the greatest recession since the Great Depression. Apple knows you don't want a Windows computer or you wouldn't be here (can you even imagine the response if Microsoft only provided DirectX video acceleration for SOME card makers but not others in order to drive up a sweet-heart profit deal between the two companies?) If anyone else tries to compete with their hardware, they sue them. Yeah, don't compete in a Capitalistic economy. Break anti-trust rules against tying two markets together in order to limit or eliminate competition instead and then cry that you're too small a potato for them to come after you while you sue even smaller potatoes that are attempting to compete against you. It's kind of like those new bank commercials where they take the toy car away and replace it with a paper cut-out citing small print about limited time offers. It's wrong but banks get away with it. What Apple does to increase profits is wrong, but they get away with it (of course the stock holders and fanatics love it and think it's SO RIGHT).
Most of the (admittedly minor by Apple themselves) "upgrades" in Snow Leopard could have been simply added to Leopard. But this allows them to charge every single Apple user in existence $29 for a minor change AND get those tight-pocketed PPC users to finally buy a new Mac from them in one foul swoop AND get them to think it's a great upgrade and CHEAP when in fact it's a minor change that should have been free, but now costs $29. It's like getting every Mac user in existence to buy a new mouse from them only without having to provide the actual mouse! And once a critical mass upgrades to Snow Leopard is achieved (which will happen VERY VERY quickly since we've convinced them that minor upgrade is so dirt CHEAP, but dollars add up for us quickly with dozens of MILLIONS of people sending us $29), ALL software developers will permanently dump Leopard like a bad habit and embrace those APIs and ensure regular Leopard is a distant memory. There will be no Universal Binary support for the new APIs in Snow Leopard and since most users will no longer be using regular Leopard anymore, there is no need to support regular Leopard. This thus ensures those PPC users have to buy a new Mac from us (they'll never give up their Mac software libraries to switch to Windows so their threats to switch are empty!)
To summarize, Apple gets $29 from EVERY Intel user out there (what's that, around 50 million Intel users? (based on Apple's own 75 million figure tripled after Intel with around 15-25 million before that) 50 million x $29 = $1450 million (over $1.4 BILLION in cold hard cash) for a minor upgrade and no hardware provided (just the same teams doing Leopard upgrades now getting paid for minor upgrades).
Now take the 10-15 million PPC users (who may or may not also own at least one Intel machine; I own one of each, for example) still hanging around and figure they'll be FORCED into buying a new Mac within a year or so and let's assume a rather smallish 20% profit margin (usually higher on higher models) and assume a mid-range point of $1500 between Macbooks, Mac Minis, iMacs and Mac Pros sold and they might expect up to an additional $10 BILLION in profits on top of whatever other sales they can normally expect from switchers, iPhone users, etc. etc. From a greedy perspective, it's absolutely brilliant! And most Mac users aren't even remotely aware of how much money such a "minor" upgrade is going to provide Apple while shedding dead weight (pesky PPC users that refuse to buy a new computer). Even if a small percentage defect to Windows or build a Hackintosh (their lawsuits against companies like Psystar keep too many people from defecting for fear the courts may take their computer away from them when they case is settled), they will still make a TON of money. Snow Leopard might be the single largest sweetheart deal in Apple's history for the rather paltry amount of work to get it (compared to major upgrades or the move to OS X in the first place). This is PURE PROFIT. I'd expect more record breaking quarters within the next year. Time to buy Apple stock again.
Yeah, keep that gravy train rolling Apple! Choo Choo! Mou-Lah!
Sing along with me now:
...When the gravy train comes rolling, for Steve, for Steve
...the golden coins keep flowing, for a new weave for Steve!
...the entire fortunes of the people will go and leave
...and fill up all those box cars...(low low voice) FOR OUR MAN STEVE!