it's not exactly "simple", since a) proper dualtouch is not possible with 4-wire, you need 5-wire or 8-wire for that (you can botch 8-wire from 4-wire and 2/4 Rs) b) as you already noticed it would need driver patches we don't want to do and c) it needs a new driver to start with, then go on with patching that one. But in the end the killer argument is: "we don't have *any* choice for the digitizer/"screen" we have to use". This whole idea is ~5+ years old now - even way pre-N900. Nobody has implemented even a strictly sw-based POC yet. Why would we take risk to implement the HW to support sth beyond such missing POC?
Stay tuned, maybe you find an easteregg in Neo900, maybe not.
/j

ps: If we'd go for a touchpanel/digitizer change, I'd much prefer THIS one