No way they start a rookie over Joe Johnson... Even if Hill and Hayward walk the Jazz are at least a 40-win team, none are as good as Hayward and Otto Porter is obviously off the table since he's leading the league in 3pt%..
There's way more viable scenarios than that lineup you just posted.
Even in the event both leave. Utah will still be a good spot for free agents at the PG and SF spots because the system in place and they're all well aware of the other pieces in place here, mainly Rudy and Quinn...
Jrue Holiday and Gallinari... lets say they're the replacements and stay healthy.. the Jazz could win 50-games, if Favors is back to 100% and playing like he's in a contract year.