I mean this has been building up since the 1970s. Hizbullah kept growing bigger, deadlier, and more hostile towards Israel. It was always going to be a bloody affair unfortunately.
How long this lasts will also depend on how far Israel wants to take it. I have a strong feeling Israel isn't going to be happy with just defeating Hizbullah and Hamas and going back to the pre-war 'normal'. It's very possible that they'll try occupying or annexing Lebanese land while they're at it (like they've done in the past) because war is so expensive and because Netanyahu needs a prize to take home to help salvage whatever reputation he has. I've even read about plans for a "Greater Israel", but I'm not sure how true that is.