100 to 1 stretched over 7.5 billion years is very long odds.
Still a lot better than 1 with 50 million zeros.
I think perhaps you misapprehend. Although not explicitly stated there is no chance whatsoever that we will go to bed some evening and see Mercury looming next to the moon. If Mercury becomes unstable, the process will take literally millions of years. If it were to happen and we maintain our current level of technology, we will see it coming a million years before it happens.
As of today, no one can say for certain whether or not it will ever occur.
Yes, but Mercury colliding with Earth is only one of many, many ways our planet can meet her doom.
Heck, we're due for a massive Yellowstone eruption. These take place about once every 600,000 years. The last one was 600,000 years ago. Think Obamacare will be bad for the country? This will be much worse! LOL!