What a bold and robust decision it was by Trinity Mirror to launch a Sunday Echo edition of its daily title in Liverpool.

This rare positive announcement from an embattled industry will be the talk of regional publishers' boardrooms across the UK this week.

But before we think "who next?", let's consider whether this seventh-day venture has any chance of surviving on Merseyside. From the outside, the facts make profitable sense:

• Close the loss-making weekly Liverpool Post that struggled to sell 5,000 copies a week at £1.

• Launch a Sunday Echo, already a popular daily brand, and double lost cover price revenues even if it only sells a quarter of the daily's 70,801 average at 50p (and it might do better).

• Add extra advertising the traditional tabloid could attract, on top of cross-selling space from Trinity Mirror's other regional Sundays.

• Take away the costs of marketing a different Post brand – noting that after launch activity, the Sunday Echo's branding will be absorbed into the daily's budget.

• Use the ex-Post's journalistic resource to produce the new Sunday edition instead, meaning no extra staff costs – and savings on what might have been redundancies.

It won't be that simple, of course, as positive predictions face the risk of potential sales cannibalisation at the weekend, with advertising possibly more spread than increasing.

But even my pessimistic sales forecast would be worth an extra £200,000 a year – not a bad launch position with all other costs subtracted by closing the Post.

If the Sunday Echo does succeed, are there any titles around the country that might follow suit?

A prime contender could be the Wolverhampton Express & Star, the UK's top regional daily with sales averaging 82,669 across six days; a new Sunday Star might also have an edition serving the Shropshire Star, its sister title averaging 43,097 sales a day.

Both dailies are owned by the Graham family's Midlands News Association, Britain's largest independent regional publishers, rumoured to have long-craved a Sunday title; if Liverpool works, it may soon be on their agenda.

There would be competition from Trinity Mirror's Sunday Mercury, but this only sells 27,523 a week, is focused on Birmingham, and won't stop the giant Express & Star brand in the Black Country.

Interestingly, Keith Harrison, the Express & Star's relatively new editor, spent several years on the Sunday Mercury as a reporter in the early 1990s (with me), and so knows the Sunday market.

Less promising would be Sunday editions in small areas well-served by weeklies: Sutton Coldfield hosted a mini-war between wannabe publisher Doug Ellis's The Sunday and the Birmingham Mail-backed Sutton on Sunday in the late 1990s; Aston Villa's then-owner lost, but the victor closed weeks later, starved of adverts by existing traditional weeklies.

Up the road in Staffordshire, the Sentinel Sunday enjoyed a few years as the seventh-day edition of Stoke's daily, but sales remained low, averaging 11,886 when it closed in 2007.

But if Merseyside's experiment works, "Sunday edition" cases could be made for bigger cities and distinct urban areas with strong dailies and no existing Sabbath titles: Manchester, East Anglia and West Yorkshire spring to mind; North Wales, Bristol and even Lancashire might not be far behind.

Steve Dyson is a former editor of the Birmingham Mail, Sunday Mercury and the Evening Gazette, Teesside