Agree with the bold. I'm not sure if Petan gets an equal shot at 4C with Copp. I think he should be clearly more talented and able but not seen as 4th line type whereas Copp is. I think Petan could slot in there but only if Copp fails. Really I see the same situation with Ehlers and Armia. They have to fail for Petan to get the shot. His best chance might be to beat out Ehlers for the top 9 spot. Just my feel for the situation. Nothing concrete.
As for the last sentence I may be getting overly optimistic but I think more than 3 ready is more likely than less. That's why Chevy didn't sign anybody.
I don't see 4th line c as where Petan will make his mark. As I've argued before I think the Jets will have what would better be described as a 3A and 3B line this season getting approx equal icetime, where the talent is mixed between the lines where one gets usage tilted to the OZ and is more sheltered likely with offensively skilled rookies and the other is tilted towards the DZ with more experienced players.
I see a lineup something like:
LLW
MP-Scheifele- Ehlers/Stafford
Petan-Lowry- Ehlers/Stafford
Thor-Burmi-Armia/Copp
Or some combination of the above.