1) Bobby Reynolds did not win at Wimbledon on Thursday, or did he?
The scoreboard showed the world No. 1 Novak Djokovic defeated Reynolds, 7-6 (2), 6-3, 6-1, on Centre Court, and after winning three qualifying matches and a gutsy five-setter in his opening round, Reynolds’s 2013 singles campaign at the championships was over.
He lost to a better player. He won in every other way one can imagine.
2) You/one can get very nasty skin diseases from bathing in dirty water.
It can be seen that both the underlined expressions start with the general subject "you/one", and therefore, they seem to indicate general truth. Can I replace the "can"s in (1) and (2) with "could"s to make them sound more hypothetical/less assertive?