Montas will be a free agent at the end of the season, hard to tell if the brewers would try to strike a deal. Civale is signed thru 2025 unless the Brewers buy him out.
Montas has a 20 million dollar mutual option for 2025 (with a 2 million dollar buyout). There is zero chance of them picking up that option. If he pitches well down the stretch, someone else will outbid them. If he pitches poorly, the Brewers would probably want to go with a younger arm even for a cheaper contract.
Civale will probably get 5-6 million during arbitration next year, so he'll be a good value.
By the end of next year, they'll also likely have Gasser and Misioroski in the rotation. Both of those guys have ace potential.
In the end, they should be set up well to have a decent rotation, but the impending loss of Adames (after this year) and D. Williams (after next year) means they'll have to go out and spend some money for veteran help at those positions. They need a power hitter badly if they lose both Adames and Hoskins after this year (and Hoskins has been awful in August (583 OPS).