I'll be very surprised if we ever see another new N scale locomotive from LL/Walthers. Just getting them to re-run the stuff they already have the tooling for is like pulling teeth...
Kato has never been hugely prolific - one, maybe two new models a year. But here's hoping Atlas finally gets things cranked back up to what they used to be 6-7 years ago.
Cheers,
-Mark