Well his support would have grown bigger and he would have been much more capable of handing Trump in the debates plus Bernie didnt have any of these big scandals hanging over him.
Sounds like wishful thinking more than anything based on tangible evidence. Bernie's euphoric campaign was protected from negativity whereas Hillary's was fully exposed to the Trump/Russia/Wikileaks smear machine to make her look very bad. Therefore there's nothing to suggest Trump wouldn't have done the same to Bernie - who would've no doubt been branded a crazy communist who honeymooned in Moscow.