for hunted i was thinking something like this.
Hunters vs Prey
Pistol w/ silencer or other attachments
In hunted 2 teams are pitted against each other in a fight similar to SND
if prey survives long enough, they win
if the hunters kill off all the prey they win
hunters will respawn in waves or something similar
prey does not respawn.
For grind....Yeah i got nothing
My guess for hunted would have been a one life only TDM/FFA game possibly with multiple rounds like SnD, or some kind of play on infected.
Hope these modes prove to be interesting, the new ones so far have certainly caught my attention especially blitz.
As Bubbagump said, if its true (ive not seen anything so cant comment on it) Grind sounds like it could be fun aswell, KC/CTF style combo could be alot of fun.
Especially if you can collect multiple tags but run the risk of losing them all if you die.