For me, 'hostel' is pronounced [ˈhɒstəl], with [ə] in the second syllable; but in Australia, I hear it usually pronounced as [ˈhɒstel], with [e] in the second syllable. I don't know if this is common throughout the world, or if it only occurs in Australia. Anyway, it is similar to the pronunciation of words such as 'polygon' (which I discussed ealier) which also nowadays have a full vowel rather than a schwa in the final syllable.
In this case, the pronunciation of 'hostel' is becoming more similar to 'hotel' (apart from the [s]), which of course is a cognate with 'hostel'. I believe this is unusual, as words that are cognate but have distinct meanings, such as 'guardian' and 'warden' and also 'skirt' and 'shirt', tend to develop distinct pronunciations'.