Browning still offers new rifles in 7mm WSM, though I'm not sure anyone else does, I think the 270 and 300 wsm are here to stay.

The .375 and .416 Ruger offer little IMO over the .375 H&H or .416 Rigby


Expand on what you mean by big bore?
IMO once you hit .375 and larger the decisions are easy, 375 H&H, 416 Rigby, 458 Lott
I don't see any hot new round coming into these markets and taking over, we have the weatherby's, 375RUM, which is now dead I believe, the 450rigby is nice, but the Lott is the way to go in the .458 caliber IMO, plus it'll shoot .458 win.mag.

also there is the .338win.mag, or .340wby.

the best round doesn't always win the race, many times the first/popular one does, and that means a lot especially if you don't reload or may one day sell the rifle or need ammo in a pinch.

btw I believe it is said that the 375H&H only needs 22" of barrel to burn that powder effectively, etc... so if you just want a handy rifle, a .375 ruger isn't required, sako has a H&H with a 21 1/4" barrel, ruger has a 23" in the H&H.

I'm not sure there are any stats on it, but it would be interesting to note how many rifles over .375 caliber or larger are sold each year, compared to under .300, I believe I once read that up until 308caliber all calibers are pretty popular, but after that sales drastically drop, ie way more 300mags are sold than 338mags, and I'm pretty certain that trend continues on up...
although they say big bores are more popular than ever before, but I still wouldn't think they're a 1/10th of deer rifle sales.