Despite what others have said, the tackiness NEVER goes away. It just takes longer and longer for items to stick. I've got some storage cabinets that are about 10 years old and if I leave something sitting on them for a month or more they stick.
My suggestion would be a barrier coat of dewaxed shellac and then poly or varnish over that. If you use super blonde shellac and water based poly it shouldn't change the color much.