I actually don't see the price as such a good deal. While its not terrible there are several variables to consider as well as the overall cost. Even just the promotional 10$/mo goes up to 120/yr, which is 20 over what sketch costs. With the benefit that sketch will not stop working.

What happens to my projects on when they go over the limits? What happens when my subscription ends?

Also we need to consider features and roadmap, these could be an incentive to subscribe.

There is also an issue with interoperability, while I can easily edit sketch in many other apps, once my subscrition goes I might have a few issues.

One big advantage of sketch over figma is plugins and integration with 3rd party prototyping tolls, these could make or break adoption of figma. As it is merely a tool in a workflow and not a complete solution.

If you do keep the price range and add capabilities for complete prototyping that removes the need for tools like invision or even atomic. Then you just kill it :D.

While the cloud tools space is increasingly interesting the handoff between them and compounded costs can get a bit scary. Which quickly make and adobe cc subscription suddenly look appealing.