H1B visa dropbox eligibility would go away if I can’t book appointment date?

[HVora]

My last H1B visa expired in July 2018. I have currently submitted DS160 and also created profile on UStraveldocs website and paid visa fees. I am eligible for Dropbox since my visa has expired within last 24 months and this qualifies for Interview waiver under the expanded eligibility applicable till Dec 31st 2020. I understand that if I book a dropbox appointment now, I can book a date until July 2021 and it should be fine. But currently it is showing no dates available and my worry is if this continues to happen till Dec 31st, will I still be able to book appointment for dropbox or will I Ustraveldocs website change my eligibility criteria after Dec 31st and not let me book for dropbox option?

[HVora]

One correction - My last visa expired in July 2019.

[snoopreddy]

Looks like H1b drop box is extended until march 31st 2021.