West Belfast 16.6% below
If one of the sitting MPs is going to lose his seat, it's unlikely he would accept it without a fight.
And not just a political battle would be in prospect, this fight could end up in the courts.
But, of course, all this speculation is premature.
The commission has yet to begin its work in earnest, and there's an obvious alternative - just widen the boundaries of the existing four seats.
After all, that's what they did last time.
Ten years ago, the same debate was going on.
Reducing the four seats to three was considered then by the commission, but in the end it rejected the idea after much agonising - and a few sleepless nights from the sitting MPs.
The Boundary Commission may come up with a "third way" but whatever it decides, it may well be too late to impact on the next general election.
It could be at least two years before a final decision is taken, and approved by Parliament.
Their provisional recommendations will probably be published early next year.
The commissioners will then put their hard hats on as the proposals go through a period of public consultation.
The last time, there was a wave of complaints resulting in five local inquiries.
In the end, the final plan was still quite radical - increasing the number of constituencies to 18 by creating a new seat, West Tyrone.
Parliamentary law states that 17 is the recommended number, although the Commission does have the discretion to go for 16 or 18.
Any reduction in the future would have an impact on the Stormont Assembly, if it is ever restored.
The number of seats in the assembly is directly linked to the number of Westminster constituencies.
If, for example, West Belfast was axed, then the six West Belfast seats at Stormont would also have to go at the next election.
Whatever happens, careers could hinge on the decision of the Boundary Commissioners.
No politician willingly wants to see his or her seat disappear.
Northern Ireland's politicians are renowned for being vocal but the one thing you're unlikely to ever hear them say is 'I'm an MP.... get me out of here'.