Dropping support for Silverlight apps

So this automatically makes all Silverlight apps from the WP8.1 days obsolete.

I believe though that Silverlight apps won't work on future versions of Windows Mobile (Or whatever it will become)

As it stands for now, Silverlight apps will still work on current Windows Phones.
 
Is there any idea if any of the big companies still supporting win 8.1 apps like WhatsApp will make win 10 apps?

I really think that there's going to be a sit and wait approach by third parties.

I can think of two possibilities, one is that they're sceptical about the income that supporting windows can bring, versus using a browser, two they've got years of data to show how beneficial supporting apps has become for other platforms, so they can weigh up whether adding a third one will make money or just be a drain.

I have a suspicion that there's app burnout in a lot of the industry. It costs money, probably doesn't generate income when compared to the outlay, and as a result, isn't worth it, on top of that, good ideas/features can easily be usurped by apple/google or any other large company.