I'm with Matty Mac on this, it all depends on where Martinez plans to use Ross. I also agree with Ara that it appears we can't expect much from Osman or Pienaar for goals.
Looking at the prem's top scorers you can see that Yaya and Hazard are the only non-strikers with significant goal tallies - I think Stevie G's figures are inflated by penalties, aren't they?:
http://www.bbc.co.uk/sport/football/premier-league/top-scorers
As for our goals from midfield, I offer Mirallas and Naismith; I would say are nearly up there with Oscar, Ramsey and Lallana. Certainly no harm in adidng another one, but I suspect Ross will grow into that role next year. Del and McGeady could also chip in next season.
Furthermore, we get a lot more goals from our fullbacks than most teams: Baines, Coleman and Oviedo have scored thirteen prem goals between them. This is a product of the tactics we use, and those same tactics see our CDM's covering back more often than their peers in other teams might. Whoever plays in the Barry and McCarthy roles, I don't see them scoring many in our system.
Having said all that, a Spurs cast-off or maybe De Guzman from Swansea / Villarreal would probably get us more goals from midfield, but in our system they'd need to be playing ACM or out wide to do that. This in turn would necessitate Ross moving back to CDM, or splitting time with a new signing at ACM.