The Welsh Premier is set to expand to 18 clubs from next season after getting agreement from the Football Association of Wales.
The move will mean just one club being relegated this season and two clubs being promoted to the league.
One will come from the southern feeder Welsh League and one from the northern Cymru Alliance.
However, promoted clubs' facilities must still meet Welsh Premier standards or have a suitable ground-share scheme.
The news will be a boost for Barry Town, who are bottom of the table after watching last season's championship-winning squad depart because of financial problems.
Barry, who lost 3-1 at Aberystwyth on Friday night, have yet to win a game this season but are only six points behind Carmarthen.
The current 17-team competition has proved unpopular as each club has an enforced weekend of inactivity because of the uneven number of teams.
The front-runners to make up the numbers from the Cymru Alliance are Airbus UK, who hold a nine-point lead at the top of the table.
The Broughton-based side have already started developing their stadium to fulfill Welsh Premier criteria, but face an inspection in the new year.
The promotion battle is far tighter in the south, with several teams vying for top spot in Welsh League Division One.
UWIC Inter Cardiff lead the table by two points with a game in hand over nearest challengers Ton Pentre.
But with no chance of returning to their former home at the Leckwith Stadium because of Cardiff City's development plans, UWIC might struggle to meet ground regulations.
Their current Cyncoed home is inadequate, although a possible ground-share with Merthyr could satisfy all parties.
With Ton Pentre also struggling to meet ground criteria, Llanelli look a good bet to join the Welsh Premier next season.
Five points off the top of the table but with two games in hand, Llanelli have one of the best grounds in the country - even when matched with current Welsh Premier clubs.