Pre order content

[Kain Mightyena]

Will frontier make the pre order rides available to purchase separately?

[Arestris]

Well, while noone can say for sure, I guess so. So they did in other games (for example the "deluxe content" in Planet zoo are the three preorder animals + soundtrack).
But no clue when, if I had to guess I'd say three to six months maybe? But that's that, a pure guess.
Also the phrasing in the last advertisement mail from Frontier sounded like that, there they wrote "unlock three thrilling extra rides at no additional cost!". That "at no additional cost" I take as another hint, that they will make it purchaseable in the future.

[StormLust]

they already did for the deluxe preorder the pack we get with that is now a dlc