Odddog, although Juddmonte own studs in France and Ireland, they only stand stallions in Newmarket (7) and Kentucky (2). I can't see that they'd stand him in the USA so unless they sell him (a la Workforce) he will stand in Newmarket.
The only real frame of reference we have for stud fees for a horse with a similar profile is Sea The Stars who retired at €85,000. However, Frankel has a better male line pedigree than STS, Cape Cross has yet to prove himself as a sire of sires and, all being well, will retire unbeaten so I wouldn't be surprised to see an advertise fee of £100,000.