The Cubs 40 man roster is currently at 46 with the guys on the 60-day IL.
Of those 46, here are the ones I find to be somewhere between definitely gone and easily replaceable:
Hendricks
Wingenter
Mastrobuoni
Luis Vazquez
Wisdom
Smyly
Bethancourt
Colton Brewer
Alzolay
Almonte
Brennen Davis
Madrigal
Killian
Herget
Hollowell
Mervis
That takes us to 30 names. Other names on there that are certainly not set in stone to be on the roster (trade bait?)
Wesneski
Tauchman
Bellinger
Keegan Thompson
Merryweather
Palencia
Arias
Alcantara (I'd love to keep him, but given our OF situation and his potential as a trade chip...)
Canario
That's down to 21 names that I would consider near locks to be on the Cubs' 40-man next year. Yes, plenty of those guys will stick around, but there is obviously plenty of room to cut bait with a guy or two and get Owen Caissie some ABs in the majors