PR 1.3 was sustaining support, the type of minor bug fixes you do right before the product is no longer supported at all. Somewhere between PR 1.2 and 1.3 was when they officially ended active support. Since PR 1.3 the N900 is in a sustaining type of support that only includes minor bug fixes that address stability and performance. Not the type of support you expect in an actively supported product.

Just over 2 months after the N900 was announced was when the MeeGo announcment was. Maybe it was 3 months, but it was clear then that Maemo had no future. For many that was when the writing was on the wall. I can see people arguing that Nokia started the EOL cycle then. By then PR 1.1 and 1.2 were already actively being worked on and instead of killing it they were probably asked to finish it and that that would be it aside from minor fixes which is what we see in 1.3. I don't think anyone is surprised that the N900 had no future the day MeeGo was announced.