I will say that under ordinary conditions, it takes quite some time for a frame to rust through. However, it can be unsightly. Newer steel alloys are more rust resistant. At the same time, newer aluminum alloys (lighter than 6061) are more prone to corrosion.
But aluminum is here to stay.
When one looks at some of the old steel road frames, it is amazing how much flex they actually have.
As I understand it, aluminum frames have evolved.
1980's and 1990's.
Aluminum frames copied steel frames. Bonded lugged design. Small tubes. Too much flex.
Early 2000's.
Welded Aluminum frames. Oversized tubes. Generally straight, but often non-round.
Attempt to remove all flex from the frames.
2010's.
Carbon Fiber Frames have started evolving to greater engineering. Oversized tubes. Full width bottom bracket.
At the same time, Aluminum frames have evolved to mimic the "modern" CF frames, probably both for stylistic reasons, but also likely the same driving forces for engineered CF also apply to engineered aluminum.
Put flex where it is needed, take it out from where it isn't needed.
Steel?
A few changes over the years, in particular with more weld tolerant alloys and processing methods. But, to a large extent, the steel bikes haven't progressed much since the 1950's.
Is one material better than others? It is hard to say. They all suffer from fatigue issues to some extent. They all suffer in crashes. And, they all may have hidden or visible crash damage that can pop up later.
Personally, to a large extent I've jumped from steel to CF, and use both, mostly skipping aluminum. I do have one bike that I ride some made of aluminum, and should have a second aluminum bike going shortly, but I wouldn't argue against its merits based on it not falling into my personal goals.