Their other choice is to let him play out the final year of his contract and see what happens then. With most players in most situations, that's generally a terrible idea...but PEA might be the one type of player who you might be better off keeping for one year, and neither saddling yourself with an albatross of a contract or losing out on having him for what is very, very likely going to be the best remaining year of his career. And that in turn may limit the amount of leverage PEA has in negotiating a contract - or a move elsewhere, particularly given that a) his preference has apparently been to move to Real Madrid or Barcelona, but b) neither of them seems likely to target him this summer. (Or at least that's what I heard James Horncastle or Raphael Honigstein suggest on the Totally Football podcast this morning.)He hasn't lost that yard of pace yet, but when it goes, it goes quick. I don't know if Arsenal have much choice because they can't replace him, but a new contract would be a big risk.
How much could Arsenal get if they sold Aubameyang? Would they be able to find a decent replacement for him with that sort of money? And would the difference between PEA and his potential replacement be the difference between a Top Four finish next season and not? It's quite a fascinating conundrum, really - and I don't think there's an obviously correct choice between selling him, extending him and letting the final year of his contract play out. I mean, I want him to stay, but I'm at least willing to entertain the possibility that Arsenal could do better without him.