I've been in a similar boat, as I used to make games in Flash.
Since Flash's demise, I've been really careful about picking a game engine/technology that wouldn't suffer the same fate. I', quite confident that HTML5 isn't going anywhere, and in one way or another, you will be able to deploy games using that technology for a very long time.
Scirra's products (C2 and C3), are HTML5 game engines (not native). This doesn't however mean that they are not fast. To be honest, from what I've tried and heard of GameSalad in the past, I am pretty certain that C2/C3 provide much more performance and flexibility.
One of the main reasons I've started using C2/C3 is because of Scirra's support. They have an awesome track record of fixing bugs regularly and keeping the engines up to date.
Saying this, one can never be completely certain of what will happen in the future - but at least with C2/C3 you don't have much of a learning curve in front of you (like some other engines).
C3 is still in beta, and the exports to iOS and Android with all the trimmings (ads etc.), still seem to be a work in progress. I personally think that its worth hanging in there and seeing what Scirra comes up with.
There are other engines out there, both Native and HTML5, that will get you where you want, but if you want a Drag and Drop Game Engine with an easy to understand eventing system and build in effects, particles, physics etc. you will not find an easier and more fun engine to use