Rumors are rumors. Personally, I'm tired of IGA made games. They all feel the same (OoE is an exception). Plus, all we will get is decent gameplay and a sucky story that will be shoe-horned into the timeline somewhere. That's his M.O. Then again, who knows. This might be the long wished for 1999 war we've been waiting for. But, it's been so long that I doubt it.
For now, to me, it's just a baseless rumor and nothing more.
Regarding a LoS3, I don't think so. LoS2 is supposed to be the end of the trilogy (or so we've been told). Once, the LoS trilogy is done, I would love to see another team to get the opportunity to create their vision of CV. As much as I like the old games, I think seeing different interpretations of CV is interesting. We've essentially have seen MS's interpretation (the LoS trilogy) with it's final chapter (LoS2) to be release this winter. I'm curious what another group will do with the series. Will they go back to the old timeline and give it true closer? Or, will they give us another reboot with their own vision of CV? Only time will tell and I'm going to keep an open mind and eagerly await the future of CV. Whatever comes next, I just hope that it is unique, yet some what faithful to the original games in terms of music and atmosphere.