I don't know or know of a child who is interested in Magic: The Gathering. Their target market is more like late teens and young adults.
If you want a more accurate usurper to trading cards, you're best looking at things like Fifa Ultimate Team[1] - which, honestly, have missed a trick in not branching into physical cards - and Skylanders. Possibly also collecting skins on Fortnite and that kind of thing
[1] a sort of virtual card-collecting football game made by EA where you open packs of cards containing football players and other items