Chris, I agree, nowadays if you want to compete for real trophies you need at least 2 quality strikers so both of these guys would be great but less likely as I think Wenger is too conservative and won't admit Giroud is not the type of striker a PL Champion would have as first or second choice. But then again Ade had one great year for us, difference being he had a much more talented squad to provide him with "easy" opportunities.
As you say we also badly need a quality wide man because at the moment our left wing is non existing and our right wing is weak not in the least because Sagna always cuts in and then passes the ball back and never makes a run to the back line and Walcott is predictable and seems to only think about scoring rather than reaching the back line.
Mertens is quality but perhaps a tat short for the PL at 169cm, although quality knows no height I guess. Personally I would not mind taking a punt on Strootman as replacement for Diaby. We need someone more mobile than Arteta. I think the only way we can go back to a 4-3-3 is by signing a real box to box defensive minded player and Arteta is not explosive enough for this. As long as Wenger feels we need to field 4 midfield players (Ramsey, Arteta, Cazorla, Wilshire) we will be too predictable going forward albeit more solid defending. So I think we should find a player who can merge Arteta and Ramsey's role. This would allow us to play more that just Walcott and Giroud upfront and hopefully a quality new wide man or worst case Ox or Podolski.