I have a triplex that has one natural gas furnace that heats the entire building.

I work in the Oil and Gas sector with a wage of 220k CAD per year.

If I'm reading the Illinois Rental Property Utility Service Act correctly, it looks like 7 days is required: "This Section does not prohibit temporary utility shutoffs in cases of emergencies such as gas leaks or fire or, upon 7 days written notice to each affected tenant, temporary shutoffs required for building repairs or rehabilitation." 

Have enough room in your panel for an electric tankless (they take 4 spots) if no gas?

***Note on Utilities: Assuming tenant will pay utilities (gas, garbage, water, lawncare) once fully occupied and no longer a househackDSM Realtors, DSM Investors, DSM Househackers, Ankeny Investors ... would love your feedback on this property.

I'm just using it as a catch-all, parking lots, industrial, car washes, gas stations, anything outside of common asset classes on here.

If you can I'd go with gas range even if you have to run gas line if it's not to hard, otherwise one made before that time.

You can check each town if there's trash cost as well as common gas and electric costs for the common areas. 

Any thoughts besides the additional cost of electric over gas.

There are some great central air options.Generally the VRF units will have hyper heat and work below zero while older heat pump designs will need a heat strip or gas backup.