Craig believes the threat of dropping into the second tier, which operates on far smaller budgets and income, deters fresh investment and tempts current owners into unsustainable spending.
"The instability it breeds has led to short-term decision making, investor uncertainty, and, in a number of cases, financial ruin," Craig told the Times., external
"Persisting with a system that restricts investment and prevents long-term growth is no longer an option
"Under a new franchise system, clubs will no longer be forced to gamble their future for short-term survival. Instead, they can focus on building a robust, sustainable, and commercially attractive sport that engages fans across the country."
Such a radical change would require approval from the Rugby Football Union Council, whose 62 members represent the wider game and is unlikely to be made imminently.
Licences for a revamped Premiership, which could be time-limited, reviewed and potentially revoked, may be a route to gradually expanding the number of teams competing.
The division consists of 10 clubs, but had plans to expand to 14 teams before Wasps, Worcester and London Irish went out of business.
Promotion and relegation between the Premiership and Championship was paused in February 2021 because of uncertainty caused by the Covid pandemic.
Although the link between the divisions was, in theory, restored this season, only Doncaster Knights were judged to have met the Premiership's minimum criteria around facilities and finances, with no other side eligible to contest a two-legged play-off against the top-flight's bottom side.