Of course interleague play shall continue! In fact, it's positively baffling that it took until just over a decade ago for it to begin in the first place. While differences in rules make the distinction between the American and National Leagues slightly more significant than the NFL's AFC and NFC, or the NBA or NHL's Eastern and Western conferences, they still all play Major League Baseball within the same association. From where I sit, there's absolutely no reason to keep the two segregated.
Those who argue in favor of returning to AL- and NL-only water fountains usually point out, often half-heartedly, that not all interleague matchups are interesting. Is this really the best you can come up with? Because I've got a secret for you: Not all intraleague matchups are interesting either. Let's be honest--when's the last time you got really fired up for Marlins-Brewers? Now let's look on the flip side: Yankees-Mets. O's-Nats. Giants-A's. Dodgers-Angels Cubs-White Sox. Marlins-Rays. Each of these interleague matchups feature crosstown or nearby foes who before interleague play began, did not play. What sense does this make? Each area likely featured, on both sides, unrequited hatred towards their local "rival". Now they actually get to duke it out. The turf war that had thus played out only by empirical comparisons can now be settled on the field. I'd gladly take Royals-Pirates three games a year for that.
What's more? Many sports fans out there are absolutists. They love one team and they hate the other. But there are fence-sitters out there. Chances are you know at least one. You may be one. You may love them, tolerate them, or roll your eyes every time one of them utters a phrase like, "Yankees or Mets, either way New York wins!" For about a century of professional baseball, their ambivalence went unchecked. Now, for at least six games out of the year, these folks will be compelled to knuck up and pick a side.
Can interleague stand to change? Sure, but only a little. I'd love to see AL rules in NL parks and vice-versa, so that fans get to see their home team play in a manner they may otherwise not have seen live. And quite frankly, you can give me a bit more interleague. Regardless, play ball!