Seeing as how the spot beam footprints were engineered to get the best optimum coverage for the areas they were designed for, there seems to be no reason, technical or otherwise, why this would change. True, the freqs involved are slightly different, but the sats are also somewhat advanced. I would suspect a modest increase in reception fade margin, if anything. This will only really affect those just on the fringes of the spots.
One of the things that DTV may be skimping on in their quest for bandwidth is in FEC. Once they feel they have more bandwidth to work with, they may increase that, which would also help fade margins.
And define "soon-".