I have a feeling, if Context disappears, you'll just see "Context" becoming a common struct that is passed around. In Python, unlike in C# and Java, the first param for a Class Method is usually the class instance itself, it is usually called "self" so I could see this becoming the norm in Go.
Under the hood, in both Java and C# the first argument of an instance method is the instance reference itself. After all, instance methods imply you have an instance to work with. Having to write 'this' by hand for such is how OOP was done before OOP languages became a thing.
I agree that adopting yet another pattern like this would be on brand for Go since it prizes taking its opinionated way of going about everything in a vintage kind of way over being practical and convenient.