From what I've read in GHL guides online, only Agency Account owners have the authority to transfer sub-accounts to another agency acocunt. So, if I purchased a sub-account from a solopreneur GHL reseller and he/she unfortunately pass away, I can definitely kiss my subaccount goodbye for good since the agency account can no longer be renewed. This just makes buying a sub-account from resellers a bad idea. Seems like WordPress is still the way to go since you will have full ownership of your website unlike GHL where you are trapped for good because of this system.
You should allow sub-account owners to transfer their sub-accounts to another agency or let them buy agency account of their own if they don't like the agency account anymore or if the agency account owner pass away.