There are plans for more hangars, museum building, helipad https://www.thestar.com/news/gta/2014/11/21/flights_of_fancy_at_markham_airport_a_former_cold_war_pilots_big_plans.html and an expanded 6000 feet runway, but it would require approval as the runway would require additional land (by acquiring neighbouring farmland) and is also restricted from expansion due by Pickering Airport plans.