For those into financials -
MLB CBT Tier 1 is $237 million next year. Go over that, you get penalized financially. Go over it consecutive years, the penalty gets worse.
Cubs were intentional about not going over this year, and the presumption is that was with the knowledge they could go over this year with limited penalty. If they go over this year, they'll go as close to Tier 2 without going over, which is $257 million.
Per Spotrac, Cubs are $83 million shy of $237. Once Boxberger ($4 million) and Bellinger ($12 million) options are saved, we're up to $99 million to spend before the first tier, and $119 million to spend before the second tier.
It's a guessing game, but take into account the $15-20 million towards arbitration eligible players, and I would guess the Cubs are looking at spending anywhere between $80-100 million this offseason for next year.
Bellinger and Alonso alone will only cut into about half of that. You'd still easily be able to afford an ace and bullpen help.