It's a dead end now anyway with e-XTR just around the corner.
Pretty much, i'll be holding off any major groupset changes until i absolutely have to (i have a "number" of RR rear mechs to choose from, and good 9 speed chains/cassettes are freely available).
I suspect e-XTR will be the next version, due for the 2015MY, so bits available late 2014. (I understand that the current XTR changes are considered to be a mild freshening rather than a full on new groupset)
Unfortunately, on the road bike It's proven to be vastly more durable and less maintenance sensitive than mechanical systems. Having proven most unequivocally that they can do it once, I'm sure they'll have little difficulty doing it a second time. Before you'd Even started typing they'd proven you wrong in that score.
And Di2 has been used very successfully in WC level CX racing. Even in thick mud.