On the physical side of things, I have close to no doubt that Isabelle will be ready for the Olympics. She can keep training up to the end of her pregnancy (with certain limitations of course).
There were two women on the gym I go to that were lifting weights all the way until the 7th month. After that it was yoga, swimming and other exercises underwater, so that they would not put strain on their joints. They were even doing abdominals until their bellies got too big and would put pressure on the blood vessels and they could pass out from it. And they were back for light exercises some two weeks after the birth. And they were no athletes.
On the psychologic side well... anything can happen. Some women really change after having a baby. And that's absolutely fine. Whatever she decides will be the right decision.
That said, I wish for a healthy pregnancy and birth, a healthy cute baby and... why not... an olympic medal (never underestimate a champion!)