Feel free to use your imagination on this topic
Cosmetic customization was progressing to be awesome…
And, Custom Arena’s eventual sandbox potential was progressing to bring us the most intuitive Halo customization experience of all time…
(Not counting Forge)
Did 343i throw everything they created in the trash bin and start from scratch?
They called it “Infinite”, but it should have been called “Combat Limited”. 
The game seems regressive (minus Bots which are great). 
I don’t think F2P was a complete mistake, but inventing (or copying) this monetization model which survives on providing limited content was a mistake.
*** What’s your out-of-the-box thoughts on what Infinite could be? ***
I don’t even know where to start (especially on customization), so I will just mention a few concepts I have:
— being able to interact with other random online players on a map environment either during Campaign or before an Arena match.
— automate controller settings. Everyone has their preferences, but in general, setting deadzones, thresholds, acceleration, and sensitivities can be calculated
— more inventive tutorial and also marines should go psycho on you if you betray one
Anyway, when we look at Halo today,
we should think “wow how this game has improved in 20 years” 
,
not “I miss older Halos”. 