Upgrading alpha to steam later on?

Hi there! I’ve went trough the dev diaries, game store page and the FAQ, but I can’t seem to get an answer to one question.

If I buy the alpha from the store now, fully knowing that it’s currently a non-steam pre-release, will I be able to upgrade it to the steam version once it’s released without having to rebuy the game trough steam?

Thought about emailing about this, but this might be a question other people are asking themselves as well, so might as well post it publicly.

EDIT: Now I noticed a quote

Once the game is available on major stores we will endeavour to make keys for those stores available to existing buyers, by using humbles system.

I’m guessing that’s a yes?