I didn't swing by the Five Below, they may not even be open right now. Not sure.
I think that the Family Dollar acquisition has been around long enough that it's pretty much been priced in. DollarTree can close the bad ones and cut their losses. If nothing else they've eliminated one of their 2 primary competitors.
What I'd be more concerned about in the longer term for DollarTree is their pricing. At some point everything being a dollar becomes a problem. At least I think that Family Dollar priced more like DG, but admittedly I've never set foot in a FD. I've been in FIVE and it really didn't impress me, maybe if I was looking for kid's items it would. But most of the stuff looks like DLTR stuff, so their markup must be relatively huge.
All 3: DG, FIVE, and DLTR could be crushed if Walmart shifts their focus from super stores and add smaller spaces like DG, 5, Tree. As they expand their online business it might make a lot of sense for them to scatter smaller stores in more places to also serve as distribution points for customer pickups. Actually I was kind of expecting to see Amazon swoop in and pick up the Sears location on the cheap.
BestBuy and Staples future will depend on what customers want. Walmart sells lots of electronics and office supplies, but there's much less variety. No doubt they focus on having the most profitable goods (markup and/or turnover) in their stores. BestBuy and Staples could see issues similar to what hospitals face. All of those little clinics can peel off the highly profitable parts of healthcare and aren't burdened by having to take on any and all ailments. But way different industry with Medicare/Medicare and the government (and insurance) involvement.
