This is a suggestion for season 2 which is not far away.
It’s getting harder to justify buying the packages as the regular cards in the chests are mostly meaningless at this point for those of us who have been spending money on the game all along. So we are paying for some tokens and a small amount of gems and coins but no meaningful cards and a large part of what we get is useless.
To make it useful and worth spending money on have the cards always have season 1 cards and the occasional legendary card that drops only be season 1 legendaries. This suggestion is for the time warp chests not the normal packages which can stay as they are perhaps with the season 1 cards added but not guaranteed. If the new skins can occasionally appear in the chests too that would be yet another bonus making the chests worth buying.