Tierney has said there are “systemic problems” facing Welsh rugby which “are really hard to change quickly” and that some changes have already been made.
Despite being a director at one of the regions, Jones says there is no option but to cut at least one teams.
“We are not a big enough nation now to have the commercial clout to [have four regions],” he said.
“We probably no longer have the player pipeline that can sustain four clubs. I don’t think the union is gong to be able to deliver longer-term the increase in their own revenue if they are going to support the game at club level and regional level.”
Regional rugby was established in 2003, initially with five teams before a reduction to four.
“With sadness, we have to come down to three or two regions to reflect the financial realities of Welsh rugby,” added Jones.
“Over the years, there’s been a fear inside the union of criticism and so difficult decisions get deferred.
“We’ve seen that with Gatland’s dismissal. I think we’re going to be seeing it as well with the decision to stay with four regions when, in their gut, they must know that it isn’t the right way forward to present a good future for Welsh rugby.”
The WRU has said the deal with the regions will “increase finances and other supporting factors to levels which will enable continued success and sustainability long into the future and by 2029”.
“This decision to sustain four regional clubs and not reduce in number divides opinion in Wales,” Jones went on.
“Many I have spoken to are supportive and are excited to see what the increased collaboration and investment will bring for Welsh rugby.
“There are equally those who say that either, objectively, the right decision has not been made or that we have lacked decisiveness in general.”
