That's awesome.
Mike Reagan said that Lionel would be taking a modular approach to building scale locomotives when they announced early last year that they were doing a run of SD40's. The SD38's followed in the next catalog and are supposed to be delivered in August.
The SD39, not as popular as the other SD-series engines, could be next to follow...
In that vein, the F40PH's which are in the current Signature Edition catalog could mean that GP40's and/or GP40-2's aren't that far off since they were all built on the same frame.