I'd at least assume that SailfishOS is likely to be (ultimately) as customizable as Maemo. At least, that'd be the hope.

With that in mind... if and/or when they reveal for certain that there will be an external keyboard accessory - and one that DOESN'T require its own charging setup like pretty much every iPhone keyboard I've looked at - I'll likely pick one up as a replacement for my n900. But not one femtosecond earlier.