i have my personal and important mails in my private mailbox, on my own domain. i use gmail as a backup and spam mail, i use it everywhere where i assume the mail can go to some spam database sooner or later.
so if i lost access to it one day, i would lose history of some confirmations from various eshops and shit like that, but nothing that would really cripple me.
i would definitely not put my family photos there and hope they stay there forever.