Most of us have computers at home that are not older than 5 years. Keep in mind that not only does technology improve but electronic devices wear out like other stuff. Your Lowrance unit is nothing more than a specific use mini computer and they wear out too. Yea, some old computers go on and on, so do some individual units, they go on and on. I’m not sure if computer companies will give you a discount on a new computer if you give them your old broken one but Lowrance does.
As far as older units and parts availability the way it works is when a new generation of units comes out with advanced features, then last years units are out of production. The wharehouse is still stocked with parts and pieces to repair these units that have been the current model for the last 4 or 5 years. So for the next 3 to 4 years or so, these parts will be used to repair units from the last generation but eventually these parts run out. Since the current generation of units are being sold and serviced it doesn’t make sense to produce old parts to repair old units that will soon be obsolete. And in 4 or 5 years the next generation of units will come out and this current generation will go through the phase out of units, parts and pieces.
You just can’t get these engineers to stop thinking of new stuff for us to use to make our time on the water more enjoyable. Eventually we just need to move on to the new features and benifits like we do with our laptops and desktop computers.