It is safe to assume that the Flash team has either left the company or moved to other roles in the meantime. The Flash codebase is gigantic, evolved over decades and probably includes IP with non-obvious licensing restriction (RTMP is an example that pops to mind). Porting to Wasm such a big codebase would require assembling a new team and figuring out some legal aspects. Both these things are expensive.
At the same time, FOSS efforts to replace Flash can at best achieve partial support for SWF content in the wild. The API surface is just too massive and poorly documented. I speak from personal experience here, having founded the Lightspark project when I was younger and with a lot of time on my hands.
Our opinion (at LeaningTech) is that Wasm can solve the Flash preservation problem by virtualizing the original, unmodified Flash x86 plugin. We wrote at length about our approach here: https://medium.com/p/eb6838b7e36f
The resulting product (CheerpX for Flash, https://leaningtech.com/cheerpx-for-flash/) is available to companies that needs to use Flash (and particularly, Flex) business applications.
Since the SWF effectively runs using the original Flash plugin the accuracy is optimal. On the hand, licensing the plugin itself is required, which means that the solution is not viable for end-users. As much as we'd like this to be different, it's unfortunately outside of our control.
Full disclosure: I am founder and CTO of Leaning Technologies, and lead developer of CheerpX