C# 8 Using Declaration Scope Confusion
In this case, It would probably coincidentally dispose of the streams in the correct order, but I'm not certain I like to rely on that happy coincidence.
From the spec proposal:
The
using
locals will then be disposed in the reverse order in which they are declared.
So, yes, they already thought about it and do the disposal in the expected order, just as chained using statements would before it.