So it costs $85k to launch such cubesat. Too expensive for almost all of us. But if the cost comes down to say $5k, I'd probably be interested in this as a hobby project.
Almost all cubesats are launched at about a 550km x 550km orbit or lower circular orbit. Cubesats (most satellites, in fact) will deorbit naturally within a few years (almost definitely <= 5Y) at that altitude due to orbit decay, mostly from drag.
Now, some cubesats will have onboard propulsion, which they'll use to extend their mission by burning back into higher orbits, allowing them to still naturally decay at the end of their mission. Indeed, they can even use remaining propellant to speed their orbit's decay.