The rumors are growing to the point, that I think we can count on a new Switch model sometime this year. Most likely we will get our next Direct in or around June and they will announce the new model then. They can also show off enhanced gameplay for certain games to incentivize people to buy the new model.
Switch sales are already going strong. With a new model, I can definitely see them surpassing last year's sales. If there are several hot new titles to go along with the new model, then that is really going to make this year's Switch sales go nuts.