Como ya han señalado otros, "como" significa "casi con seguridad". El artículo de wikipedia citado por @Matt es un buen comienzo para casi con seguridad y sus sinónimos.
Sin embargo, existe una sutil distinción entre casi seguro (o con probabilidad 1 ) a siempre [resp., Entre con probabilidad cero a nunca ].
Imagine an infinite series of i.i.d. random variables which are head a.s. (=with probability 1), tail with probability zero. It is possible in such an infinite series to have a finite number of tails although the probability for tail is 0, as the empirical distribution of the series remains 1-0 (only a finite number of instances out of infinitely many). On the other hand, when one says that the series is always head one means that not even a single tail occurs in the series.