Decline and the ending of Buddhism

http://www.lawsofthenature.com/GotamaSasana.aspx

I share with you the following passage taken from the page of the above link > The Buddha said that after His parinibbaana, only for 1,000 years will > the monks be able to acquire the analytical knowledge (Patisambhida), > or what we know as Arahanthship or deep knowledge. Then, as time goes > on, they will only be able to attain Anaagami (Never return). And then > only Sakadagami (Once return), and finally, only Sotapanna (Stream > enterer). With the death of the last disciple who has attained > Sotapanna, the attainments will disappear.

Here's my issue with the above. From what I understand is that after a certain period of time after parinibbana, the maximum attainment that one could achieve reduces from arahant to anagami and so on. But this is illogical because if a person attain anaagaami he/she will only have at most 1 life where he/she will become an arahant which makes the above statement false, unless it means that the person will be born as a deva maybe having a very long lifetime until the next Buddha. This is confusing.