Given that Chanderpaul is nearing 37, his omission isn't very surprising: he has no chance of playing in the next World Cup. The death of ODIs may have been greatly exaggerated, but the death of bilateral ODI series has not been. Where they are interesting, it tends to be because they are played before the Test series, lending them context. Piggy-backed onto the end of the Tests, they are essentially meaningless. So it makes sense to ditch Chanderpaul, in this form of the game at least.
Sarwan and Gayle, however, are both 30, so clearly haven't been dropped for reasons of age. Sarwan has struggled for form for some time now, and was never fluent at the World Cup. Gayle was, but the view that he doesn't care much has always lingered, albeit unfairly at times. If you are trying to build a new team with spirit and work ethic, it probably makes sense to dump Gayle. Keeping him in, for all the brilliance of his batting, risks sending a symbol that it's fine to act in such a nonchalant way with so little apparent passion for the West Indies (with his decision to arrive back from an IPL stint only two days before a Lord's Test perhaps the best example of this). To a degree, Gayle is probably slightly unlucky - he strikes me as a man for whom, like David Gower, endless hours of training would be counter-productive. Nevertheless, dropping him is a powerful symbol.
Yet the most disheartening aspect of the selection news concerns two all-rounders who should be integral to a West Indian revival. Both Dwayne Bravo and Kieran Pollard will miss international fixtures to play in the IPL - and the West Indies board don't even bother threatening not to select them in future. Of Pollard, the statement even said, "It was mutually determined that Pollard would be best served by being allowed to hone his T20 skills in the Indian Premier League, which will bring future benefit to West Indies cricket". Who do they expect will believe that?
With commitment levels like that from their best players, it is no wonder the board have said they want to make it 'special' to represent the West Indies again. And it's why talk that the West Indies won't exist as a cricketing entity in 2020, but a series of nations, continues to linger.