PL should have allowed 5 subs given that teams will be playing every week twice almost throughout the ssn.Anyway seeing the schedule,i think the teams with strong youth base are going to benefit.
Most of the teams involved in UCL and EL matches after PL ended have not yet come up with Pre ssn. plans.So,i guess for most of them it would be friendlies only in England probably against Championship and lower rung teams just like they had before the PL resumed post COVID lockdown