If by "outer years" you mean adding void years to the contract, then yes. If the restructure is done within the current terms of the contract, I believe it can be done without player consent unless they could possibly make less money. That would only happen if they added a bunch of incentives that the player didn't agree to. In most cases, it's just converted to a signing bonus (cash up front) and prorated through the remaining contract.
I believe Hines did this with his restructure by having more incentives for the possibility to earn more if they are met and reduce his base + signing bonus so he had to agree to the terms.