and we have a confirm from slush many minutes later so it can not be stolen correct?
Firstly
If I'm awake and using my computer I know about orphan races when they start.
.. so most of the time.
(Yes I watched the last orphan race and was actually about to post about it when antpoo confirmed the BW block)
The block after an orphan race decides the winner ... most of the time:
The only time it doesn't decide it, is if another orphan race occurs on the next block (which is ever so extremely rare) and the sides of the 2nd race are on both the different blocks in the first race ... so yeah this just about never happens.
Also even more rare, an orphan race can be more than 2 blocks in the race, but I don't know if that has ever happened yet.
So yep, it's pretty certain that as soon as someone sends out the next block, the orphan race has been decided.
--
Now, when can a block that's not in an orphan race be lost? The main reasons would be:
1) If no one actually knows about the orphan race coz the other side didn't send out their block soon enough (or at all) ... they could then confirm their own block and thus orphan the previous network block ... if they managed to find the next block before anyone else did.
So the bigger the pool, the greater their chance of doing this ... if they used this tactic
2) If you mine a block that the majority of the network will consider invalid ... at some point ... then yep your block will be orphaned.