Again, as long as the CONTANGO condition doesn't change.
There CAN be periods of times when/where contango changes to backwardation. During these times, VXX - are you ready for this? - will be moving UP (albeit LESS than VIX moving up). But alas, these backwardation times are abnormal. Sooner or later it will go back - reverting back to the mean - to contango and start marching downward steady as she goes again.
So take your pick of the background condition and I will tell you - actually not me, but the way VXX is set up to behave - what VXX will be doing.
The REAL question is when would the background condition change? I'm sorry but I haven't met anyone who can tell me reliably when that would be.
I'm very bearish on VXX, but I don't want to give out a false impression of VXX will ALWAYS be going down lower. This simply isn't true. However, it IS true that in NORMAL condition of contango set up, VXX will always eventually go down lower. There, now I feel better.