Concerns have been raised over player welfare as the regions prepare to have their squads severely reduced.
Cardiff, Dragons, Ospreys and Scarlets are working towards squad budgets of £5.2m for the 2023-24 season and £4.5m in the following campaign.
The Welsh Rugby Union said it anticipates regional squads to be around 44 players.
However regional head coaches have said the real figure is expected to be closer to just 38 next season.
The shortage for the 2023-24 campaign - described as a "reset" by Cardiff head coach Dai Young - is raising concerns over the demand on a smaller group and the potential dangers of relying on academy players.
Coaches work on the basis of having 20% of their squad unavailable due to injury at any given time during the season.
However international calls ups to the senior and under-20 teams could then leave regions struggling to field a match-day squad of 23 players, particularly during the autumn Test series and Six Nations.
The Welsh Rugby Union (WRU) insists talks are ongoing to ensure that does not happen.
Ospreys head coach Toby Booth said: "We'll end up with a squad number of about 36. We can have up to 44 but I can't see us being able to afford any more than 36 to 38 maximum.
"All regions are around that [number] as I can't see how the numbers fit [the budget] otherwise.
"There's gong to be a massive reliance on academy players, which in some cases can cause greater problems because you may be putting in people who aren't quite ready.
"On the flipside, those who are ready will get game time"
In 2021, Cardiff were forced to field academy and semi-professional players in their Champions Cup tie against Harlequins during the Covid-19 pandemic.
There are concerns they may be forced to do the same again next season with Dai Young's squad reduced from 43 to 46 players down to between 36 and 38.
"That's where we are, that's as far as the money goes and we have to deal with that," said Young.
"There is potentially a wellbeing issue and it does cause us concerns but the reality is that we can't get more out of the pot.
"When we sat down to look at this, our preferred squad number would be between 40 and 44 but that wasn't based on the budget as we didn't know what the budget would be. Now we're trying to make the best rugby sense out of the agreement."
Next season will be a "reset" year for Welsh rugby
The Welsh Rugby Union insists player welfare is "at the heart" of the governing body.
"I can understand concerns of player welfare and those conversations are ongoing," said acting chief executive Nigel Walker.
"We are not going to have a position where during the Six Nations next year there are [only] 10 senior players and 10 or 12 under-20s making up the numbers.
"Clearly that would not be the right thing to do. We have some work to do in certain situations but our intention is to make sure those squads are sufficiently deep to ensure regions can put out senior teams when they lose players to the national squad."
Scarlets have begun offering players formal deals with boss Dwayne Peel saying they hope to retain about half of the 20 players who are out of contract at the end of 2022-23.
Peel expects to have a squad of about 38 to 40 players in 2023-24, reduced from almost 50 currently registered as they absorb financial cuts.
Dragons believe they will be the least affected by the cuts given the relatively small size of their squad following 17 departures last summer.
"I don't think our squad size will change dramatically because we've got one of the smallest squads anyway this year," said head coach Dai Flanagan.
"Unfortunately other regions may have to manage that change but that gives us an opportunity to play youngsters, back them and provide an opportunity.
"Continuity is big for us. There was a big change last year before I arrived but we've got good youngsters, good quality professionals and then a bit of stardust who will hopefully still be here."