You're making assumptions. That has not yet been determined.
Well.. In one of the many (yes, I know it's hard to find, as there is so many) threads about this exact same thing.. two well respected members of the community (GeneralAntilles being one) said that at the Barcelona Maemo Summit a Nokia Vice President of one of the departments over the Mobile section said, quite specifically in no unclear terms, that the N900 will not be getting M6.
And to someone else, I have found no where that Qgil said that M6 was possible for the N900... what I have seem him say is that we should wait until the SDK release, or at least more information, about M6 before we speculate what will or won't happen with the N900.
I will be surprised if the N900 receives M6 when a VP said that it would not (and I'm not inclined to disbelieve the General) - however, that doesn't mean that Nokia hasn't planned, or isn't working on some way to combine the two, or make M5 continue to be usable and unique past the M6 release.
At this point, we simply don't know what the future holds for the N900.
Also, to the OP regarding "history"... The N770 came with OS2005 and was then upgraded to OS2006. The N800 shipped with OS2007, and while the 770 wasn't supported, Nokia did create a OS2007HE which was basically OS2007 for the 770. Thus the 770 got 3 full OS upgrades.
Now the N800 had OS2007 out the door, and when the N810 hit the market it had OS2008. The N800 got the update to OS2008 as well... and then both the N810 and N800 got the minor update to Diablo.
So.. looking at the "history"... the 770 got 2 supported, 1 unsupported OS upgrades, the 800 got 2 + a minor, and N810 got a minor.
Now.. the trend does seem to be going in the wrong direction.. but at the same time it's not exactly unheard of for Nokia's "tablets" to be receiving OS upgrades.
This thread, and others like it, are mostly pointless at this time. Nokia is guaranteed to have already heard the screams of others, myself included, in one of the other M6 to N900 threads on this forum.
Quim asked us to wait.. I don't see why that's such a big problem. If lack of N900 upgrades is enough to make you not want an N900... then wait for the m6, or buy an Android. If the N900 does everything you want it to now... then there isn't a problem here. There will always be something better right around the corner.
After HTC G3 put into market, HTC official annouce that G3 can upgrade to Android 2.1. But we have no news from NOKIA after N900 release about the system upgrade strategy.
There's been no news from Apple about whether their new OS will work on older iPhones either. It's very uncommon to announce support before you've actually finished development.
One of the positive aspects of the "AppStore model" is that it's a new revenue stream for handset manufacturers that their income isn't solely generated by hardware sales. The phones are not the end product, but they become content delivery machines that can keep generating revenues for the AppStore owner.
This is an added incentive for them to:
a). Support the existing phones/devices as long as possible.
b). Upgrade their old handsets to be compatible with the AppStore model, enabling them to generate income from the old models.
c). Design their products to be as backward-forward compatible as possible, while incorporating new features to enhance the new products.
Apple nailed the above aspects well... so I'd say there'll be more iPhone-like traits in future smartphones (including from Nokia).
One of the positive aspects of the "AppStore model" is that it's a new revenue stream for handset manufacturers that their income isn't solely generated by hardware sales. The phones are not the end product, but they become content delivery machines that can keep generating revenues for the AppStore owner.
...
Do you suggest that hardware manufacturers would make more money from the small cut they get from a customer buying 5-6 new applications for 4-5 dollars each than they would make if they force you into buying a new $500 handset 6 months earlier than you normally would? I don't believe this makes sense.
Nokia and Apple sell hardware; the apps, stores, open source, is just the bait to make their hardware more attractive. I am sure that when Apple come up with how to change the iPhone (the upgrades we've witnessed are insubstantial compared to what NITs have gone through, for example), they will abandon backwards compatibility.
OTOH, software companies like MS maintain compatibility to an unmatched extent.
