One of the reasons they gave for the delay of switching to wasm was that nacl had threading support while wasm didn't (wasm supports running in workers, but com

One of the reasons they gave for the delay of switching to wasm was that nacl had threading support while wasm didn't (wasm supports running in workers, but communication can only happen asynchronously through message channels, no advanced multi threading capabilities like sharing memory etc). Then spectre happened and delayed the wasm threading support of browsers even further. Chrome has experimental wasm threading now, but other browsers don't. So now the non-Chrome launch happens without usage of wasm threading.