It would be nice, if there will be some more trinkets in future, that will be obtainable with credits. Ive seen alot of players who already have all mercs and dont need any more credits for trade ups, because they are happy with their current loadouts. So, what about trinkets, what can be bought for, lets say 50k or as reward for some actions done in game, like heal, revives, supplies and so on.
Something like this:
Teabag: Id really like to have this one 
http://i.imgur.com/8k7Bemx.jpg
Broken heart: maybe add it as reward for few kills with defibs?
(look at my amazing drawing
)
Ammo box: As reward for some ammo resuplies to your teamates
(think about an ammo box of skyhammer with chain to mount to your gun)