Just a couple of days ago, Microsoft evangelist Nuno Gomez confirmed unambiguously in an interview that all existing WP handset will get updated to Windows Phone 8 Apollo once the update rolls out.
That sounded a bit too good to be true, though - Microsoft had only confirmed that older devices from the first and second waves of Windows Phone will support apps in the Marketplace even after the update, but it wasn’t clear whether the older devices themselves would ever get the update. Turns out, Gomez just made a mistake rather than revealing something ground breaking:
By unintentionally giving this unexpected hope though the Microsoft evangelist might have done more bad than good. His statement opened up a huge debate on what it would mean for Windows Phone if older devices don’t get updated, and that seems to be the likely tacit scenario as Microsoft remains silent on the issue. In either case, you’d do better to cut those expectations away - if Redmond decides to update you’ll be in a pleasant shock, but otherwise you’d save yourself a disappointment.
source: Nuno Gomez