With all the new bullets and cartridges out there what will stick?

6.8 spc
6.5 Grendal

450 Bushmaster
458 SOCOM
50 Beowolf

I would love to set up a poll but I cannot membership has it perks.

they will all pass.

edit your original post, now you can pop in that poll.  imo 6.8 i think will be around.

Considering both 50 Beo and 458 SOCOM are already getting "old" as they have been out since 2001 ....

You might be surprised ....

I think some of the new loads will do well as the AR15 keeps gaining in popularity.  

It seems like 6.8, 6.5G, .50B, 458S at least are fairly well established and are growing in popularity and scope of production every day.  6.8 has the benefit of being backed by major ammo manufacturers, but the others getting more press time with bigger and bigger companies.  I don't think they will die.  Not sure on the .450Bushy yet, as it is so new.  It was released by Bushy though, so that is a bonus for them, plus Hornady is making the ammo.  They have a jump on the others from when they were in their infancy.  It started with major backing.  We have seen some calibers go kaput too, like the .499LW (yes, everyone will say it is in redevelopment, but it is not out there right now and will be basically a new caliber if it ever comes out again), and others I am sure.  Seems like most do ok if they get some backing, even if it is small manufacturers.  The 6mmAR looks like a great caliber which is a 6.5G necked down to 6mm, but not sure it will get a strong market share, or the 7.62x40 or other "wildcats" that are probably great calibers, but may remain a niche market.  

6.5 Creedmoor by far will be gaining more popularity among competition shooters than any you have listed.