What if - just follow me here - what if this wasnt a small field test and the intent was to gauge large reaction & prime the base for the possibility of change.
There's little reason to believe that's actually the case here Instagram rarely, if ever, pushes out massive changes without any explanation even if it's an understandable impulse given that trust in Facebook is at an all-time low. It also doesn't help that a number of Instagram users are still salty about losing their chronologically-sorted feeds in the first place.
All of the trends that we've seen suggest that in the not-too-distant future, people will be sharing more into Stories than they will into feeds. And that the whole market across all of the Stories type of product will be bigger and a market where people are sharing more moments from their days into Stories type products than into Feed type products.
But it's worth remembering just how important the Stories format is to Facebook when you think about why Instagram would do these kinds of tests in the first place. In a world where Stories is the most dominant format, of course it makes sense to also change up the dynamics of the main feed to make it look and feel a bit more like Stories.
Even News Feed, the most iconic Facebook feature, was initially hated before almost every other service ended up copying it.