@MitchL does have a point though.
At some point, the Cubs are going to be beset with paying quite a few now-inexpensive players much larger sums of money. I said exactly that in 2016. Even with a situation as flush with cash as the Cubs are...they are indeed not going to be able to pay everybody.
2020 I'd say would be when it begins in earnest, but next year things start to happen.
2019
Quintana ($10.5M team, +$1.65M)
Strop ($6.25M team, +$400k)
Bryant (arb, $10.5M this yr)
Hendricks (arb, $4.17M this yr)
Chavez (FA)
LaStella (arb, >$1M this yr)
Baez (arb, >$1M this yr)
Montgomery (arb, <$1M this yr)
Schwarber (arb, <$1M this yr)
Contreras (last yr pre-arb, <$1M this yr)
Edwards (last yr pre-arb, <$1M this yr)
Almora (last yr pre-arb, <$1M this yr)
Wilson (FA)
Heyward/Darvish/Rizzo/Zobrist, total drops roughly $10M for one year only - this offsets the above somewhat.
But 2020...yowza, because you have a bunch of key guys hitting arbitration or in their 2nd year of it, and Rizzo's contract climbs to $16.5M if the team chooses the options, Morrow's option is $12M. Now, Lester provides some savings, but still.
To me, and I will admit I don't know the Cubs' system as well as Cub fans do...but by 2020 the Cubs will be "graduating" players that were drafted by the time they started no longer drafting at the top of the order, but the bottom. To me, the numbers I'd bet will indicate, you'll be bringing up "good players" and no longer bringing up "great players".
You better hope that the system is producing a LOT of good players I'd say by 2020/2021 at the latest, and hitting on intl signings you've made recently. And you're also counting on the vets that are locked up continuing to produce.
Theo's done a good job playing this all out to front end guys he could front-end when the kids there now were still cheap...but that window is closing - and a lot of hard decisions are coming. You're probably talking about trying to buy out arbitration years with some, and rolling the dice with others or cutting bait early if forced to by the farm not producing.