I mean, they may well release some specific info around that time, to drum up interest. But I just doubt that the festival tour has anything to do with the new album, so I doubt any new music will be played.
I would imagine the album will be released later in the year, with a supporting tour next year.
It is possible that they could say something earlier, and especially since MP doesn't take the lead in the announcements anymore, it is possible that things might be handled differently. But if they aren't planning on releasing the album until towards the end of the year, they probably wouldn't want to release the details about it too far in advance, which was the issue that MP/DT had with the ToT info leaking 2 months before they intended to make the announcement. They didn't want to much speculation going on, which still happened - I remember people worried that ToT was gonna be a Christian album, based strictly on the song titles and the fact that MP had been working with Neal Morse - how wrong they were!
So I would expect that they would probably hold off on making any announcements until they're within a month of releasing the album.
An interesting side note I noticed is that (with the schedule as it is listed now), they are gonna be on tour during the same exact period they were for the 2003 tour with QR. Not that this means everything else is gonna mirror 2003, but an interesting detail nonetheless.
I'm pretty sure that in recent years the festival dates never showcased new music.
They haven't played material that hasn't been released since 2002 (SDoIT was released a few days after the start of the European tour), and really since 1996-1997, when they previewed material that later ended up on FII. With the advent of smart phones and digital cameras (nevermind those sneaky taping guys!) it's highly unlikely DT will ever preview unreleased material live ever again.