It’s not eight.
It’s seven open spots.
I like having 7 open spots. (I wish we had more good prospects, but different issue). What do do with 7?
1. Sign 3-4 FA's. Heh heh, Imai, Bregman, Castro, Fairbanks!

. Won't be those four, obviously, but 3 or 4 will go to FA's.
2. Use 2-3 for waiver guys. As other teams complete their FA additions, a whole bunch of 40-man rosters will get overfilled, so guys are going to get waived. Having 3-4 spots open mean the Cubs will be able to pick up some interesting guys. Hopefully there will be a few pitchers with both talent and options, and Cubs "infrastructure" will be able to create some value? I like that space to take some shots.
3. Save 1-2 for non-roster invites. Assume Hoyer will sign a group of non-roster guys. If things work, one of them will look good in camp, will make the roster, and will end up being productive. Having 40-man space provides opportunity.
So having the spots I think provides some fun opportunity to add/create talent.