I wouldn't rule out future Blue Water conflicts at all, and you can be sure the Navies of the world will not do so either. Sure tiny diesel subs might be the sexy stars of the moment, particularly when the US and Iran are rattling sabres over the Gulf. But in years to come, with a resurgent Russia, China on the up, the US having to protect it's finger in various oil pies and all the other players too, at some point the sabre rattling may go to the next level as resources dwindle and the protaganists have to make a choice between fading away and making a move to stay on top.
Not a nice scenario, but certainly one planners for future procurement of weaponry have to consider.

Chock