Appears the direct ÖBB night train from Vienna to Brussels will be canceled on February 2nd, and according to the ÖBB hotline, it is completely uncertain how they will handle this. The replacement connections would involve other train operators such as DB and SNCB, and it is unclear whether they would accept the tickets for their part. So maybe I'll be unable to attend #FOSDEM this year, even though I already booked the tickets early and was certain I could go there.