That's a hell of a question. It would depend on how they draw the districts, how many teams per district, and in what direction or how big of a radius. If they go east of Morris it would likely include JCA, Provi, maybe Lemont and Crete(?) If they go north they could stick with the existing conference with teams like Sycamore, Kaneland, and not sure who else. Again it would depend on how far the district lines would reach. As it is Sycamore is a solid hour north of Morris.
Assuming they would try to keep the districts close in terms of size of schools take a look at the 4A-6A maps for playoff teams on the IHSA site and Morris is kind of on an island. Using those maps the closest schools to form a district would potentially be Morris, LaSalle-Peru, Ottawa, Coal City, JCA, and Provi. As you can see this creates a huge spectrum in terms of competitiveness, at least as far as football goes. I would say you could throw in Lemont and Crete as well but both of them are in much closer proximity to so many other schools that they wouldn't be likely.
Morris would most likely get put in a district that stretches to the west to include Sterling and Geneseo as they've played in a conference with them as well. This makes the most sense as far as size goes but far from fair if we're talking travel.