Why does the OS matter if the applications work concurrently on MeeGo and Maemo 5 devices with Qt?

If Qt is the glue, and MeeGo (formerly Maemo 6) devices are going to have significantly different hardware, wouldn't it be a smart gesture for Nokia to keep the N900 in play with updates to the Qt stack?

Now, if Qt gets to a point where Maemo 5 can't be used as efficiently with it, wouldn't that be a case for something like a Mer project to come that rebuilds the shell/app space in Qt to better eek compatibility and performance from N900 devices?

I hear and see the fears, but for some reason, much of this seems incredibly blown way off base considering what we know about the platform and what it does and will support.

Or, is my PR language coming out too, and I'm just blasting hot air?