New figures emerging from the Catholic Church in Scotland show that within 20 years, the Archdiocese of Glasgow will have only 45 priests.
The figure is less than half the number needed to minister to all their current parishes.
The news was confirmed by a consultation document drafted as part of an investigation into the Church's situation in Scotland which began last autumn.
Examining the South Deanery, in Glasgow's south-west, as a test case, the document was quoted by the Scottish Herald as saying: "It is conservatively estimated that in 20 years' time there will be 45 priests in the archdiocese, which means roughly five in this deanery."
The South Deanery, which includes Our Lady of Lourdes Church in Cardonald, is the place of worship for approximately 5,700 regular worshippers, and is home to an estimated 28,000 Catholics.
Given that the deanery currently contains 12 parishes, at least seven of them would be affected in some way.
Several options have been proposed in the document, including the creation of five parishes with more than one church building each, or possibly unifying all the current parishes into one, with a single active church building, leaving the others defunct.
Priest numbers have been declining faster than parishes have been closing for some time. Priest numbers fell from 196 in 1991 to just 85 in 2012, a drop of 57 per cent. The number of parishes in the same period dropped by only 13 per cent from 108 in 1991 to the present figure of 94.
The Church consultation is being conducted with no specific time-frame in mind.
Speaking to Christian Today, church spokesperson Ronnie Convery said: "It's very open ended. There's no hit list, no secret list of parishes to be closed. There's no timescale or targets or documents that say 'we want to have a certain number of parishes closed by this date' or anything like that."
The Archbishop of Glasgow, Philip Tartaglia, was quoted by the Scottish Herald as being very wary of large scale centralised planning initiatives.
"I always have the fear that the local and the particular and the unique will get lost in someone else's big idea," he explained.
"So we must try to be both courageous and sensitive, sometimes a difficult balance to achieve. We need to do what has to be done, but people must not be trampled underfoot."
Explaining the causes of the current consultation, while Archbishop Tartaglia did partially attribute it to the priest numbers situation, but also highlighted another cause.
"The other big factor is that communities across the diocese have changed a lot over the decades both in nature and in number," he suggested.
Expanding on this, Mr Convery talked about how the current system of parishes had not evolved significantly since the 1950s and 60s. "That was when the church in Glasgow, seeing these new housing developments being built, quickly built a parish to serve them.
"In the last 50 years those housing estates have been depopulated, often because the quality of housing was terrible. However the parish churches remain.
"We still have priests serving very small decimated housing schemes in the north of the city, whereas in the south, we have had churches that have had to be expanded because that's where people have been moving.
"We just have churches and priests in the wrong places."
In that respect, Mr Convery suggested that the current process was no different from what many other charities, government bodies, and commercial organisations regularly do.
"We're looking at where the people are, where the needs are, and we're then looking at what and where our resources are, and we try and map the resources onto the needs."
Overall, demand for church services in the Glasgow archdiocese has been declining. Between 1991 and 2012 there were drops of 14 per cent in attendance at funerals, 39 per cent at baptisms, 41 per cent at Sunday mass, and 54 per cent at marriages.
Mr Convery admitted there would probably be fewer parishes in the future, but he said the more important thing was quality over quantity.
"Part of what this consultation is about is creating more vibrant parishes. There may be fewer, but they would be busier with more people, more happening, and more vibrancy."
Mr Convery suggested the changes would revitalise evangelism and the church, saying: "It's better that communities are served by a resident priest. At the moment we may be spending too much time and effort on practicalities of dealing with leaky roofs, rather than focusing on the core message of what the church is about."
As part of the ongoing consultation, Archbishop Tartaglia is meeting with all currently serving priests in the archdiocese over the Lent season.
Responses from parish churches on the consultation are expected after Easter.