The Welsh Rugby Union has announced a four-team increase to the Welsh Premiership from the start of the 2016-17 season.
There will be no relegation at the end of 2015-16 from Welsh rugby's top domestic tier or for the following three terms.
Any team hoping be promoted from the lower-tier Championship must meet the A licence criteria by 18 December, 2015.
Combined regional/club teams will enter the British and Irish Cup in 2015-16.
Leading Welsh Premiership clubs have entered the British and Irish Cup in the past.
But new teams - Ospreys, Newport Gwent Dragons, Cardiff Blues and Scarlets Premiership Select sides - will take on English and Irish opponents in future.
The WRU will also "lobby" to keep the LV= Anglo Welsh Cup alive in 2016-17 with the regional Select teams taking part.
Pontypool finished fifth in the 2014-15 Swalec National Championship, but like second-placed Swansea and north-Wales based RGC 1404 (fourth) their facilities meet the standards set out for the Premiership.
Bargoed RFC topped the National Championship in 2014-15, but their facilities do not meet the standard specified for teams in the Premiership.
Neither do those of third-placed Merthyr, but backer Sir Stan Thomas has pledged the club would reach the standards required to obtain an A licence by mid-July, 2015.
A new Welsh Premiership Challenge Cup will also be launched in 2015-16, to be played on the same weekends as British and Irish Cup fixtures.
WRU chairman Gareth Davies said: "The entire focus of this exercise has been to strengthen Welsh rugby and I can promise we will continue to seek ways to preserve our heritage, while improving the rugby pathway from the very top through to the grassroots."
WRU head of rugby Josh Lewsey said: "There has been a long and detailed debate on these issues involving all the stakeholders and I believe these decisions by the board are based on what is best for the game.
"We are helping create a Premiership within which players can develop their talent through teams they can identify with as part of the fabric and history of the game in Wales."