Seedless grapes already exist, but I suppose you could now insert the gene into other plants/varieties to make those seedless as well.

I'm thinking more about how big ag companies could use this to prevent farmers from saving seeds/propagating a copyrighted variety (though I don't know if that's common with any crops where the seed itself isn't the end product) or maybe more charitably, preventing their copyrighted plants from cross pollinating neighboring fields of the same species (e.g. ruining that neighbor's non-gmo status).

Finally, this could be useful if it can be "switched on" i.e. by deliberately polluting an invasive plant's gene pool with this gene and then switching it on to stall the invasive's population growth. But I think most invasives are perennials, so would still need to be removed some other way.