As @CSLKennyNI said above, Rookburgh was initially forecast to open at the end of June. The hotel discount was voided for any annual pass holders starting their pass from the 01.08.2019. Therefore, with Rookburgh initially planned to open in June, some passholders would have received 35% discount on Charles Lindbergh for a month's duration. (for example my pass expired on the 17.07.2020 and therefore if the area had opened late June then I would have got hotel discount in July).Hotels are not allowed to open prior to the 21th of May, so a immediate opening is unlikely in my opinion. In addition, I believe they are adding the days missed on the annual passes, which would cause some passes with hotel discount being valid on opening day. (If you are nor familiar with the discounts: Annual pass holders received a 35% discount for the on-site hotels, which is no longer part of annual passes purchased in July or later. Therefore I expected Rookburgh to open AFTER all annual passes with a discount have run out). Maybe they will delay the opening until no discounts are applicable any more; on the other hand, I still expect some delays for some works of the area.
Therefore I highly doubt they will delay the opening until no discounts are available anymore, as with the current pass extension scheme europa are offering, if Phantasialand choose the same policy, passes with hotel discount will be valid way into 2021.