No deal can be made until after the season after Steelers do not franchise him a second time. edit: team can negotiate a long term deal while on 2nd franchise tag again up to approx. July 15.
Once he was tagged and the deadline passed in July 15 he can not sign a new contract now. Can only sign the franchise tender and play this year for Steelers or team he is traded to.
If he holds out all year he is not a free agent next year either. That is why it is assumed he returns week 10, I think he needs 6 games to accrue enough games to have this year count towards free agency.