Firstly, in the Japanese version of the Direct, Iwata revealed that a new version of the Fire Emblem: Trading Card Game will be releasing in Summer alongside Fire Emblem If.
Characters shown include Marth (illustrated by Daisuke Izuka), Caeda and Tharja. On the official Fire Emblem World site, you can find a card of Wrys too.
Secondly, Code Name S.T.E.A.M., a new strategy game also developed by Intelligent Systems, will be compatible with Fire Emblem Amiibos such as Marth, Ike, Lucina and Robin. By scanning in one of these Amiibos, you can play as the corresponding Fire Emblem hero.
Lastly, if you didn’t manage to buy a Marth Amiibo when it was first launched, you’re in luck as more stock will be arriving later in the year, in North America at least.