The obvious answer is that corp IDs based around stealing or scoring (Jinteki PE, Haarpsichord) would become more powerful, but what other effects would it have? If you didn’t have to give up a deck slot for that 3/1, would you run it? How would you change your runner deck knowing the corp you face will have 49 cards plus 20 points worth of agendas?
Corps would be worse across the board because of the decrease in efficiency. Larger agendas would be better because they would affect deck size more noticeably.
There would be a noticeably lower agenda density in all decks, though…
TWIY* would become the new home for fast advance.
Fast Track would be in every deck.