I also think we need to consider the fact that some of our youngsters are getting much better - who would have foreseen (outside of the club) Bellerin improving as much as he has done? And Giroud and Monreal have improved significantly. When Wilshere is fit then he always looks good, and of course there are wild cards like Coquelin! We definitely need some signings, and definitely need to strengthen the squad as a whole, but we can't forget about the players we already have as well... Personally I'd like to see us sign competition for Giroud as striker, as although I see Welbeck improving, I don't see him improving significantly to compete with Giroud and while Walcott will improve as a CF, his lack of strength will always let him down in a lot of tight games in the centre, so his best position is RWF. We definitely need a DM/physical CM type player in some shape or form, whether back up/competition for Coq, or a step up on him. It's critical, and we can't go into the season relying on just Coq for the whole season. Other positions we may need to sell when we buy. Keeper for example, I can't see Wenger selling Ospina a mere year after signing him, and after 6 months of him being 1st choice. But whether he'll want to ditch Szczesny after spending most of a decade developing him, right at the time he should be peaking? It's tricky. Same with CM, we could bring in a Worldie, but it would mean ditching Wilshere, and potentially restricting Santi and Ramseys playing time/development.
Pretty much agree with you that we are on an upward curve. Also I think we can improve the squad without upsetting the apple cart. We have a good group of players like Ramsey, Coqs, Bellerin etc that we can built the team around, but we still need a few others to bolster the squad in case of injuries. The way we are playing and the squad players we have now, i do believe that we will do much better next season, which should mean we will be competitive in the league.
Agree about the upwards curve of the young players. In a nutshell a DM / Combative CM is a must and it has been for several seasons. Wenger got lucky with Coq this season, but as mentioned we can't rely on him all season. Other than that I think the MF is fine, we have lots of options in there. I'd like to see a World class striker come in, but I don't see it happening. I think we'll see more of Walcott and Welbeck rotating with Giroud, but my preference would be for another CF and keep Walcott and Welbeck on the flanks. In some ways though it's a good problem to have as any one of Giroud, Walcott, Welbeck or Sanchez can lead the line