Ospreys coach Steve Tandy will stay until at least 2020, say chairman Roger Blyth and managing director Andrew Millward.
The new 'exciting' Pro14 tournament could expand again in the future, says Welsh regional rugby chief executive Mark Davies.
Ospreys centre Ashley Beck is ruled out for up to four months after suffering shoulder injury in pre-season training.
Swansea City could take over ownership of the ground where they and Ospreys have played since 2005.
Audio & Video
Former Wales captain Gwyn Jones says the Pro12 expansion is a gamble despite the money pressures on the Welsh regions.
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