Obama had some structural advantages in 2012 because he was the incumbent.
Obama already had a lot funds in the bank, and names on his lists, from his huge 2008 win. Romney is rich, but was starting from essentially scratch in building his volunteer army and voter database.
Obama was able to start investing in his national campaign infrastructure way before Romney because he did not have to win a primary first. Almost every early dollar Romney brought in had to be spent right away on short-term ads and organizing to make sure he won the primary.
And Obama was able to access the national Democratic party infrastructure from the beginning. Romney did not have access to the national Republican infrastructure until he won the nomination.
The effect of all this was that Obama was able to take his time and build all his software custom, while Romney had to wait until the last minute and buy things from external sources.
By the way, 2012 also demonstrated that shortcomings of Super PACs. They can spend a ton of money on TV ads, but they're no help at all with the (increasing important) data operations, because they are forbidden from coordinating with the campaign. While Romney was supported heavily by Super PACs, almost all of Obama's fundraising went directly into his campaign--where it could pay for core technologies.
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As for lasting progress, the U.S. Digital Service is not going to last beyond Obama, at least not in its current incarnation. It's housed under the Executive Office of the President and it is a political operation--their job is to make sure that the President's policy priorities have good technology. Obviously a new administration (of either party) is going to have different policies and priorities.
There's also the ephemeral "Obama magic"--he's just built a good reputation for using and appreciating technology. Pretty much no other candidate in the 2016 race has that (at least yet). Alpha geeks might not stick around for a more "old school" president like Hillary, Jeb, etc.
Things look a lot better for 18F because it is housed under GSA and it is intended to be politically neutral. And there's also a push on right now to get agencies to hire more digitally savvy people directly into staff roles--those would also be more likely to persist into the next administration.