Seems like it'd be smart to have a version with a "dead-man timer". Something like every X hours a beeper goes off and you have an hour to actively interact with the beacon (button, pin code, etc)
Also if something happens to incapacitate you for several hours out in the wilderness, you'll mostly likely be dead before help arrives--even with a beacon.
A locator that can be remotely activated (periodically wakes up to check for an activation signal) could be pretty useful, but I think it would mostly be used to locate bodies. Requiring solo hikers to carry something like that might be good alternative to parks requiring rescue insurance.
It's not as ideal as it does ultimately require a human to raise the alarm.