Lots of landraces are "hybrids". You have to remember that the terms "sativa" and "indica" are only the broadest of guidelines and in no way scientific at all.But I was looking for landrace sativas and not hybrids because I am planing my next seed project and I am only going to use land races if possible.
If a landrace establishes between two different existing strains it will carry elements of both. I.e. hybrid.
You should also remember that the variety in a landrace can be quite marked. Don't expect supermarket standardization here
Some people would argue that the terms "sativa" and "indica" are actually misleading. I find them useful, provided you don't get too religious about it.
For instance you can get very short flowering sativas (eg. Mediterranean) or ridiculously long flowering ones. You can get intellectual creative weed, or stuff that will mess you up and S-C-A-R-E you (not necessarily a bad thing!) Witness some of the more electric Mexicans (I've seen them bring seasoned hardcore tokers to their knees, praying to Jesus for it to wear off ) or some Thais. Or you can have joyful blissful stuff that will make you feel like you're in a Bob Marley Reggae video.
Probably best to describe what effects you are after, rather than just say "sativa".