And my biggest fear as a worker is not longevity but my marketability to gain new jobs. If unions make it easier for me to get hired and promoted without consideration of tenure of other union members I'd probably be interested in joining
I think research might be a little difficult since there are a lot of things that can impact a company's longevity and success (however that's being defined) that have nothing to do with employees (unionized or otherwise), but I imagine a good study might be able to account for that to some extent.
There's also the risk the union basically exploits the young and old by driving their wage from shitty to zero (by setting them too high to bear for anything but the most able bodied middle age). This pretty much mimics my experience younger working construction; union gigs set my wage at '0' by making me the outgroup. Being exploited by middle age union workers is bad for longevity imo.
In the US auto industry (which is the relevant industry for the article under discussion), it hasn't. Companies like Toyota that employ non-union workers in the US are doing at least as well as (and have arguably done better than over time) the Big Three.
For some definition of "successful", yes. But their definition won't necessarily be the same as the definition used by the company's owners or management.