In soccer, is it possible that a 4th substitution would be allowed for extenuating cirstances?

In the Athletic Bilbao vs. Real Betis game today, a fan threw a bottle striking the Athletic keeper in the eye. The game was suspended in the 75th minute with Athletic winning 2-1. The talk is that they will finish the game at a later date. Presumably, if the game goes on, Athletic has used up all three subs. If Armando cannot return to play (pretty nasty eye injury), would it be posible for the league to allow another keeper to take his place?