According to Blake Oestriecher from Forbes, WrestleMania as a two day affair could become a permanent change going forward.
Read more below about two days of WrestleMania possibly becoming permanent, from Forbes-
Another potential permanent change would see WrestleMania expand from a one-day event to a two-day affair as there had been “water cooler talk” within WWE about making that switch in order to accommodate WWE’s rapidly growing roster. In fact, the circumstances brought upon by the impact of COVID-19 essentially forced WWE to switch to a two-hour format for this year’s event, and that could become the new norm going forward due to WWE’s overabundance of superstars.
There’s a lot more about WWE/NXT, it’s a really good article. Check it out at Forbes.com.