You have a point, but considering Betamax tapes only stopped production in 2016, (the recorders in 2002) and the proliferation of dvd / Blu-ray, etc is much higher I think 20 years is safe. 30 however…

But is there any format you can promise every part of it will be in production in 20 years ?

Amazon still lists some refurbished vhs players but…

It doesn't seem very reasonable to draw conclusions about longevity from any comparison of a rather complex machine like a Betamax deck (that cost a huge amount of money to buy) to something rather simple like a modern Blu-Ray drive ($100, ish).

It seems much more reasonable to assume that Blu-Ray hardware will continue to be produced until something else (what?) actually supplants it for cold, off-line data storage.

(Also, too: The compact cassette is dead as fuck and has been for decades, even with the niche resurgence in recent years. Yet new machines are still being produced, and so is new tape stock. The format is 61 years old.)