Then you have misunderstood me. Support != updates. The N900 with Pr 1.3 works well. More updates will probably make it even better, but for a mobile computer/smartphone the N900 is superb as it is. In other words, by purchasing a N900 now you will get exactly what Nokia promise, and more to be honest.

When you buy a phone when it is brand new, you are in it for the ride of updating the OS/software. Today the N900 is old and mature, but fully operational with very few bugs straight out of the box. But who knows for sure? Nokia is still updating the 5800, there may still be a couple of updates on the N900 as well, but it is not that likely because the N900 has only sold a small fraction of what the 5800 has, and Maemo is dead as far as further development go.