I agree the 300 wsm is about the best thing going in a little short, fat 30 that will fit a short, light action. Very accurate and excellent use of the powder. I have never built any guns off that case but have chronographed quite a few for people wanting to know what there gun would do. I do know the 30-338 win mag and the 300 win mag very well though and have never chronographed a short mag that would shoot with either velocity wise. The short mags are great for what they are designed for and I keep hearing people say they will shoot with the big boys, but I have never seen it. I can tell you about a lot of sad faces at the range when they saw what the short mag would actually do after the guy at the shop said it would shoot with the 270 wby, 300 winny or wby or 7mm wby. All I tested came in between the standard '06 cases and the standard magnums. I know I have yet to see one that would beat my Gibbs rifles which are blown out '06 cases as far as velocity goes.
I love the little short mags and am in the process of putting the stuff together to build a lightweight, short action backpack deer rifle probably in the 7mm. I understand from the start it is just a step below the big magnums velocity wise but I don't care. It is right there close to them and I really don't think the deer would ever question it. The ones I chronographed were extremely accurate. If that is the size case your looking at then I would not hesitate to build a rifle chambered in it.
Predictions are difficult, especially when they involve the future