There's still a bit of life left in Blake yet. He hasn't had a stellar year by his old standards, but he has been winning matches consistently, so his ranking is comfortably back into the top 100, and it is certainly likely to stay there for at least the next 12 months, as long as he can continue to play tournaments.
Why consider retiring in the immediate future? Doesn't make much sense.
Next year could be his last though, especially as I suspect that he will be more aware of his own limitiations now, compared to when he was a little younger and at the top of his game (look at Dent's sudden decision quit). Playing the Olympics is a reasonable motivator, and he could perhaps retire at the US Open, while his career still has dignity.