...won't support current devices because of the hardware (not having 1GB Ram, dual-core or w/e) then please tell me how is going Microsoft to put Apollo on low-end devices if the requirment has changed o__o?
Well, we don't actually *know* that WP8 won't be supported on current devices. But if it isn't, there are multiple potential reasons why this could happen. Memory is one, lack of interest by manufacturers in rewriting the drivers for legacy devices is another. And finally there's simple economic interest of the carriers and manufacturers - even if they could write those drivers, would they bother since it won't get them any additional revenue?
If memory is where the real problem lies, then I'd expect WP7 to be sold concurrently with WP8, with WP7 Tango targeting the budget market and WP8 targeting the high-end market. If it's simply a matter of drivers and WP8 is perfectly capable of running on 128Mb and 256Mb devices, then it's possible that we may new see Lumia 400's, 500s, and 600's running WP8, with the 700,800, and 900 lines getting upgrades but legacy HTC and Samsung devices left behind. Samsung in particular has a history of this - the Galaxy S phones were being released until shortly before ICS came out (the Nexus S is a Galaxy S phone), and the Samsung-branded Galaxy S phones won't be getting ICS while the google-branded Nexus S has.
One more thing. Why they are keep saying current apps will run on Apollo? Do they mean Apollo apps won't run in Mango/Tango ._.?
It's possible that native Apollo apps will be based on the WinRT framework that they've announced for Windows 8, which is a cross-platform framework that allows the same app to run on both a mouse-based desktop and touch-based tablet, on x86 and ARM processors. Microsoft hasn't announced this, but since the other Win8 systems are using this it seems possible that a Win8-based WP8 would too. In which case sucn apps are very unlikely to ever run on Mango/Tango since these OSs lack WinRT support. But it appears that Microsoft has made sure that the WP8 phones do support the Silverlight-based framework that is used for current WP7 phones, and that it is compatible enough to run pretty much all of the WP7 apps. Microsoft is testing these in an automated environment so there may well be some glitchy apps when WP8 finally ships, but things should be generally solid.