That's an interesting individual of whom - until this thread came along - I had never heard before.
Of course all the relevant points have already been mentioned, and I particularly agree with Indy's Brother here.
I could see her included in a Pat Roach-type role rather than a Cate Blanchett or Alison Doody-type of role.
The problem is just that it is a very fine line the screenwriter would have to walk to make Gwendoline Christie look appropriate, as in "fitting into the narrative", have some substance, rather than just being showcased as some freakish hench(wo)man as we know them from the James Bond 007 films. The latter I would disapprove of for Indiana Jones - hence why I am now somewhat worried that Lucas might find that idea appealing and pen an entire plot just around her