You have the option of cutting the counter edge and getting a range. This replaces both the cooktop and the oven. I'd like the new Bosch induction range with knobs. Bosch HIS8055U 30 Inch Freestanding Induction Electric Range with 4 Heating Elements, 10 Cooking Modes, Sabbath Mode, QuietClose Door Hinges, Convection, Metal Knobs, Digital Display and Temperature Probe (ajmadison.com)

There are two aspects:

1) will a new oven fit in the existing cutout? It's possible, wall ovens are fairly standardized so a newer wall oven may fit.

2) will a new oven be compatible with the existing cooktop? Cooktops and wall ovens that can be mounted under the counter are often Paired with each other so certain Kitchen Aid ovens will fit under certain Kitchen Aid cooktops. It's possible a newer KA oven would fit under the current cooktop, but it's possible that they have changed a bit and a new one will not fit under it.

I would probably investigate those options before having to replace the countertop and remove a cabinet, or a cabinet face.

The Kitchenaid KOSE500ESS received a reasonable review from CR but is not designed to be installed under a cooktop per the installation instructions.

The top-rated Cafe CTS70DP2NS1 can be mounted under a cooktop and Cafe will even provide an up-to-$300 subsidy to make it fit. Check the installation instructions to verify.