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  • John Otterson thinks this is interesting:

You can test what we have done so far and change the PlayerSpeed parameter in runtime.

From

Cover of Unity 5.x 2D Game Development Blueprints

Note

Although the text says "[Y]ou can test [...]", I believe this means to say that the parameter can now be changed in runtime in code from a script, not dynamically changed in play mode from the interface for testing purposes.