It seems it can only be used with statements: (1) is impossible because it's a command, and so I predict it would be impossible with questions and hypotheticals too. And indeed it is; these sound terrible:
Do you think she's going to get the prize, deservedly so?
Her husband will be pleased if she gets the prize, deservedly so.
(3) is egotistical beyond the bounds of normal social acceptability. It could only be said as a joke.