Well, if it's structured right, then it won't be an advantage - it would just replace some other tournament that the player would otherwise count towards his ranking. If done right, that provides a stronger incentive for players to view it as "I can play davis cup instead of some other tournament", instead of viewing it as a burden for the sake of country pride. Sure, those players would have one more tournament to choose from, but I don't think that's enough of an "advantage" to worry about.
I'm curious as to how they are planning to do it though - I can't easily imagine a system that is both fair and useful. But if they do, good for them - it seems like it could be possible.
I think that's a big "if". Of course, if they come up with a fair point structure effective as an incentive, good for them.
However, probably due to my lack of imagination, I don't see how they'll come up with a fair and effective structure.
If they want to provide a strong incentive, they'll have to assign a significant amount of points (as you mentioned, enough to compensate the points he would get from a tournament he would have played)
and also probably to assign different points for the matches of the different rounds/groups: higher the rounds/groups, higher the points.
Then, the stronger the team where a player belong, the more chances for him to earn points (probably with less effort in terms of number of matches to win to earn the same points from a tournament).
So, it's not fair to the players who would have no chance to even advance to the world group, or whose best possible result would be just the annual first round elimination. (e.g. the players like Baghdatis, Gulbis, Lee, Niminen, Horna, Dancevic, maybe Murray,...,etc.)
The regular tournaments are in principle open to anyone depending on his own ability.
The chances to play Davis cup matches are not.
