What the stats tell you about Vardy is that he if continues scoring at his current rate then he'll hit about 35 goals. xG tells you that he'd be outperforming the mean from the quality of his chances created by about 18 if he continues like this to the end of the season. I don't recall a player ever scoring more than 10 (Messi) than xG predicted for them.
His xG only predicts him to score 22 if he reverted to the mean from now on from the chances Leicester are creating for him currently, which would take him back to match his best performance against the mean previously. It's not impossible for him to continue this vein of form but it's exceptionally unlikely.
Vardy's best performance against the mean was +5 (rounded) in 17/18 so if he repeated that he'd hit 21 - 22. If he could match Kane's (+9) or Messi's (+10) best performance against the mean then he'd hit 25 -27.
So unless Leicester improve their chance creation significantly or Vardy has the most remarkable season by a striker in the last 6 years then it wouldn't be sensible to bet on him hitting 30. I think the sensible estimate would be 22 - 27.
Any corrections or data for other xG models welcome.
Source
https://understat.com/player/755