Officially, yes, but...

Looking at Wikipedia's article about the Mayflower trilogy, it says that the book is planned to be called Rasputin. Card's website has said, at least since 2010, that the book is in progress. However, in 2015 the co-author of the first book died. As far as I have found, he has not said what's going on with the book since.

In 2010, he said this:

Lovelock, on the other hand, is waiting for me to solve some story problems. I know the next volume focuses on the cat assassin Rasputin, and that he comes head-to-head with his assigned target, Lovelock. Beyond that, there's a lot to discover! Not ready to write it yet. To Kathy Kidd's great chagrin.

_source

I am betting that this is not ever going to happen, but we'll see.