N900 is not a phone, its an internet tablet with phone functionality. There's are no other equivalent to N900 apart from the developer only N950 which is not publicly available, and poses its own set of restrictions.

N8 and E7 both runs symbian and there's numerous threads of hate with such devices when proud N900 owners got their devices replaced with either one of those. There is an alternative if you don't like the N8 or E7, that is to sell it and buy another second hand N900, though you may end up paying the differences.

I do not know if you'll be charged by Nokia should your device be out of warranty for them offering you N8 or E7. You may want to ask Nokia Care directly.