For impoverished Gazans, Fatah's participation will likely mean some improvements in some areas.  Fatah is corrupt but not as ideological as Hamas. Fatah is a dictatorship (Abbas was "elected" in 2005, and no elections nor opposition were allowed after that) but not as violent as Hamas.  And Fatah has a better relationship with both Israel and Egypt.

Will Egypt continue their shut borders with Gaza?  Unlike Israel, which is an enemy state to Gaza and with no expectations of a border crossing, Egypt should open its borders for trade and people.  Egypt occupied Gaza before 1967 and never had a war with it, but considered Hamas an enemy because Hamas' connections with the Muslim Brotherhood.