if you are remotely fussy/discerning you may want to build your own bike up. The OP has already talked about that. You can of course have any brakes you like, that way.
BTW the postulate that 'hub brakes are not available' is ridiculous. SJS have lots, also Isons and 'the Cycle Division' are wholesalers that most LBSs will have an account with, and they supply a plethora of SA hub brakes.
Just 'cause you can't buy it in wiggle or Evans this week hardly means it ceases to exist.....
To put rim failure into perspective, in relation to the number in use, I see at least as many mangled/broken disc rims as I do worn-out rims from rim brakes.
The argument about rims 'failing unexpectedly' could be levelled against other parts too...like, er, tyres....The cure is exactly the same, too; buy decent ones and inspect them as required. BTW half-decent rims are cheaper than decent tyres and need less attention by far.
If you look after your brakes, they will not wear rims anything like as fast as otherwise. If you neglect your brakes (regardless of type) eventually something dreadful will happen; with disc systems the whole system can eat itself or you can be left with no brakes. The system that tolerates complete neglect with least trouble is arguably drum brakes.
Also, this view may not be flavour of the month (and maybe the OP has already made his mind up/followed the herd, so I am wasting my time even mentioning it) but there are plenty of good reasons
not to want disc brakes on a touring bike.
cheers