When will the collection agency give up? SOL ped, credit report expires soon.?

My charged off account is past the statute of limitation and will fall off my credit report this year. I am saving money in anticipation of owed income taxes. However, the IRS will only expect taxes once the collection agency resigns to not collecting (please correct me if I'm wrong). Will they give up once the 7.5 years has ped? What's their incentive for continuing efforts to collect after that point?