that is kind of a tricky question. the only way you will know the answer is if you take the trim off, and inspect along your windshield channel, on all my cars it was always worse than the bubbling appeared, but then again i get my s130's after they have had extremely abused lives.
So lets say you take the trim off and the bubbling is only one area. Meaning it has not spread all along the windshield channel. If this is the case you can do a minor repair by cleaning that area with a wire brush or spot blast it, followed by treating it with a rust inhibitor like the POR products. Once you complete that you can use a body filler, sand, prime and paint (if you can match the original). With this method you should not need to pull the windshield out.
But in other cases like myself, if the damage was more than meets the eye you will have to pull the windshield, trim, wipers, and plastic grill for extensive metal replacement. I hope you do not have to go that route, as I hate it every time.