The first interesting thing that emerges is that the biggest losers may well be the Liberal Democrats.
It is ironic that if the AV referendum had succeeded and if the Libdems were to poll anything like the 20%+ vote they have come to expect in a General Election then they would have probably been by far the biggest gainers in Westminster seats. However the plan to cut the number of MP's was coupled with the AV legislation but was not subject to the referendum. So even if the Libdems do not suffer the same meltdown in votes that they had in the Scottish and Welsh elections they are likely to regret allowing the Conservatives to place this alongside the AV bill.
The analysis by Democratic Audit also using the Boundary Commissions attempts to give us a possible likelihood of what the new Welsh constituencies may look like.
BlogMenai has added a useful critique of the analysis which is well worth looking at (you can use goggle translate if your Welsh like mine is shamefully not up to reading it directly).
As I have said this is largely an hypothesis and it may well see a big difference when we vote again in 2014. Or we may be voting earlier as the Libdem wake up to the fact that even if they overcome the current toxic effect of being coalition with the Tories and they recovered the percentage of the vote they received in 2010 they are still likely to lose nearly a quarter of their current seats. Indeed in the next few months this may well be the biggest strain on the coalition. However I don't think the public will regard a stand purely on the Libdems self interest to kindly