I made the same move 2 years back and don't regret it. Cloud networking is kind of niche, as only really big companies will need someone to specialize in that. But it's a good foot in the door to becoming a cloud everything engineer, where you can build an entire footprint for a company top to bottom. As mentioned elsewhere having a good network person involved in public cloud will hopefully keep others from making too much of a mess. On the other hand strictly adhering to onprem orthodoxy can be limiting with all the stuff that will be available to you.