The Boston Symphony Orchestra have just announced that Andris Nelsons is to become their next Music Director, beginning as Music Director Designate in the 2013-14 season. He takes on the full role in the following season on a five-year contract that commits him to up to 12 weeks of performances each year. The full press release is below.
The CBSO have confirmed Andris will stay with them until "at least 2014/15 on a rolling contract"; they will make an announcement about future seasons later this year.
While it's possible for one conductor to handle two orchestras, this makes it less likely that Nelsons will be available for the Berlin Philharmonic opening in 2018.
BSO press release: