Hard to imagine him getting the necessary playing time in such a vital juncture in his development in a forward group of Tevez, Morata, Dybala, Zaza/Llorente/Matri. He brings something to this team no other player we currently own can - raw pace. Seeing Coman's performance is a pretty stark reminder of how much we lack a pacey, man beating forward. It's pretty crazy to realise how well we've done for so long with a relatively slow attack.
The to loan or not to loan debate is pretty perplexing. Given a year on loan he would undoubtedly explode in one year or the next. However, Juve seems like a positive environment to play in where limited game time might not compromise players form/development like we think. Youth can earn their place and contribute if they have they have the talent to take their chances. All that's needed is patience. Morata and Pogba were also slowly integrated as starters and they came to Juve with more age and experience than Coman. Look at Sturaro. I'd say he's improved remarkably in the short time he's been here despite limited game time. He was thrown in the deep end during a desperate situation and proved he can give Allegri certain guarantees. Coman might be so lucky too.
You can see a big difference between Coman's first game of the season and this one. His decision making, movement and strength over the ball against Napoli are marks of maturity he didn't have when he arrived. He's still quickly developing despite not getting much of a look in since week one. Keep him and continue this measured approach I say. The wealth of experience he's getting playing his role in a winning team with so many quality, experienced leaders and role models is as valuable for an 18 year old as it is rare.