I'll stick to my N900 for the years to come.
There is no need to upgrade it as long as PR1.2 comes out and QT4.6 will make a bridge between MeeGo and Maemo 5 so that the flow of apps doesn't die out.
There's a darn good chance I'll get something newer in the next six months. Maybe an N8 to try out later in the year if there's no more details regarding whatever the MeeGo device will be. If the N8 reviews poorly after it ships, I might get an Android device.
I generally buy at least one phone a year, often two, and sometimes three, so I'll almost certainly getting the MeeGo device if it's got a physical keyboard. Funny that I'm perfectly happy with my laptop which will be 4 years old in a few months.
I really should learn to sell the damn things when I'm done with them rather than letting them sit around. I have a E61, E62, E71, 6650, E75, and N810 still sitting here gathering dust and losing value. My SO is using my 5800. Yeah, it's an addiction.