Granting the knock-down drag-out fights we are all familiar with (I concede they may be unrealistically frequent in the comics, but given there are mindless monsters, some are inevitable), some changes would be needed.
One we may already see, since Superman comes from Metropolis; Batman, Gotham; the Flash, Central City; Green Lantern, Coast City, etc. Obviously people have spread out more, which helps minimize the risk. (There being no out-of-universe reasons to invent cities. 0:) Gadgeteers could easily invent stuff that would enable communication and transport to decrease the cost of doing so.
But there would be all kinds of things to do. Invent new construction materials, to make it easier to make all the buildings basically earthquake proof. Invent better alarm systems to get the heroes in quicker. Organize plans to teleport the bad guys out of populated regions if at all possible. If not, high strength heroes would work to throw them out if at all feasible. And, of course, taking the bad guys out quickly is a priority.
Not to mention the number of superpowered construction workers.