In the good old days, before it was mandated that navigation devices had to be available at retail with removable security modules, the cable operator could choose the current best technology and put set-tops in the homes of his subscribers. All subs then had simultaneous access to the new technology. No one was disenfranchised. No one's consumer electronics equipment was made obsolete. A possible disadvantage is that subscribers could not own the set-top box.
Careful analysis suggests that only the retailer is missing out.
The only way to facilitate the retail purchase of set-top boxes is to freeze the application of technology with standards. While software downloading helps track the advancement of technology for awhile, it doesn't solve the problem. Just as with personal computers, processors become more powerful, memory becomes cheaper and software expands. There is a significant hazard in all of this for cable. If the same folks who brought you the regulations that require you to freeze your technology so that subscribers can purchase the set-top box at retail also require you to open up your system to ISPs, the danger is immense.