As someone who is in the software industry, I can say that the only way to run a software business successfully is to have minimum version support levels. A company who will support any version, even one ten years old, is going to be carrying a lot of heavy baggage. The training requirements for the support personnel, who are generally lower skilled labor, are way beyond the value to the business. Customers who languish on older versions beyond the service life are on their own. Upgrade or move to another platform.
Obviously, the danger in that is that some customers will eventually move to another platform but the cost balance probably makes it more profitable to let those customers go.
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