James II was inept enough as it was. His support in the UK vanished so fast that a serious civil war was never on the cards - the man made every mistake that it was possible for him to make. William III on the other hand was a remarkably canny man.
As for Austria and the Balkans - well, by this point the Ottomans are in serious trouble, being beaten by the Hapsburgs, the Venetians, the Russians and the Polish-Lithuanians. Austria shouldn't get bogged down anywhere and besides the French threat was too obvious.
Let's not forget that warfare outside of Eastern Europe at this time (the Polish hussars were still sweeping all before them) was still largely positional and formalised. Marlborough wasn't yet in charge of the British forces.