Just to clarify, compiling for 64bit is not a major task - we already build 64 bit for consoles, and have a windows 64bit internally. So this really is just about swapping the runtime over.
To me it's more important than most other things right now as the default download for Linux is now 64bit - and has been for a while. This means if you even want a user to run your game, they have to manually install a stack of things. This is horrible. So for such a small change, it's one we really want to make. if it were having to spend weeks or months changing and updating things, then I'd totally agree.
Also, because we're not talking about having both 32 and 64bit (like we would need with Windows) there is again no additional IDE or compiling work needed - it's just building for 64bit.
As to plugins. We've already been talking internally about open sourcing some of them, but have yet to decide, but it's defiantly on the table. There are some issues we thing we need to resolve first however.
We're already getting vendors to do their own integrations now (as shown by the new Game Analytics plugin
https://marketplace.yoyogames.com/assets/5179/gameanalytics )
(audio streams, surfaces etc) Not all these things are available to extensions yet, and the runner needs pretty major work cross platform to allow it. Because users can do this themselves (create their own textures, surfaces etc) this is not something that is
currently high on our list.
Web Sockets is definitely high on my list, but not something we can currently do just yet, we've too many other things going on - some of which will become clear soon I hope. HTTP and HTTPS is implemented across everything though?