I really loved his "Alvin Maker" series (most others don't appeal). After the last one, which I think was about 5 years ago, it seemed to come to an end, but there still was opportunity for more.

Does anyone have any insight as to whether he plans to do any more books in this series?

It's a great series.  I think he will eventually do another one.  I don't think he's officially said so, but like you said, there's definitely room for more.  I've read almost all of his books over the years, and when he leaves room for sequels, he usually gets around to them eventually.  I'm personally waiting for another book in the Ender's Shadow series...

Speaking of which, I have books 1 and 2 of the Alvin Maker series available on my shelf for anyone interested, as well as Book 1 of Card's Homecoming series. - Just a shameless plug for my shelf!