You have to look at the cost also. 57 million for a plane going to serve for 15 years only?Mk1a is not supposed to be doing mk2 or mirages like multirole perform. No matter how much HAL try to market it that way or we want, to the user it should always be for the role it was intended for, as mig21 replacement. That means primary use is putting Mk1a in front of any rogue jet that is looking to encroach inside the countries airspace. Mk1a is not supposed to venture outside the country airspace and like the mig21 it should have limited ground attack capability.
So basically extra mirages should not interfere with any current and future mk1a orders theoretically if fund is allocated. It can eat into mk2 numbers though which is the true fighter class and able mirage 2k replacement. But with thin sqn numbers this can be a temporary solution for a jet the IAF still considers a frontline platform.