I doubt neutrions are it. In the same spirit however, string theory predicts that ~11 dimentions actually exist, not just the 3 we easily perceive. Personally, that's my main hope for something tangible existing beyond what we frimly know. If string theory is ever demonstrated, then there is a whole lot of stuff hiding right under our noses.
BTW, even if some version of String Theory turns out to be able to give a reasonable account of the universe we currenly observe (a far-from-obvious outcome), any extra dimensions that it might posit—either at the Planck scale or even larger—aren't going to give us a way out of here. After a handful of years, you can stick a fork in us...we're done.