It's only the few decision makers that are relevant, it isn't like a government where there is something to be gained by bribery on each level, even the lowest civil servant. Unlike corruption in a nation, we are not talking about a culture of corruption that involves millions. There's no point in bribing just a lowly FIFA official or bureaucrat, most you can buy that way is easier access to the big boys.
That small group of corrupt decision makers is now rapidly diminishing, and there is not a long line of eager replacements, especially now that the feds are looking over their shoulders.
And not just the (US) Feds -- the Swiss are conducting a separate corruption investigation relating to the 2018 and 2022 world cups, and other governments are interested as well. Essentially, the fact that the World Cup is a big national prestige event and that past corruption has been brought into the light means there is likely going to be intense scrutiny from all sides going forward -- sure, for every beneficiary of corruption there are lots of losers, and when those losers are major nation states, they have a pretty impressive ability, if they turn their will to it, to address any problems, especially if given the convenient excuse provided by actual corruption to prosecute.
To me, Blatter was just the face of corruption. I simply cannot see someone from inside FIFA being able to resolve the corruption problems, mostly because these people are the problem. This isn't a new thing, and this isn't something that arrived with Blatter. Some journalists have been investigating corruption in FIFA for decades. Hell, most countries have been a part of it. It's only surfacing now because the bribery is so blatant, and our bribes simply weren't enough.
People will cheer and say that "we finally did it", but I cannot see anything truly changing. The only way FIFA will change is through the authorities.