Some of your concerns were addressed earlier in a different thread, Recurring Revenue and Long-term Viability. The person who wrote that opening post was convinced to let go of his fears.
Of course, change is the only constant in the world. I can’t tell you that none of your fears will ever come true. In fact, as you note, technology has a distinct tendency towards becoming obsolete. As for myself, I have seen the people at Sense invest repeatedly in keeping their customers happy, so I trust that if/when my box becomes obsolete, they will have some kind of path forward.