Those should work well - but, Need to ensure they are sealed very well, to not let moisture in there and end up trapping water in between sleeve and wood pole. They should fit snuggly on the wood. The sleeve needs to be a good foot, up above the ground level and covered by the sidewall sheeting, to keep moisture from entering around its edges.  

I would buy some foundation coating and paint all the wood poles bottoms to a couple feet above ground level, put the plastic sleeves on, then use some of that elastic rubber tape used around doors and windows to seal up the connection or, I'd buy some Ice and water shield membrane, used on the edges of home roofs and wrap the poles with that. It's a rubberize membrane that should shield the soil, moisture and insects from the wood pole.

As pointed out - it all depends on soil type, environment and geographical location as to how long wood will last in ground conditions. As deep as the frost went this hear, up here - it's very tough on pole barn construction.