The statistics that I have seen put the survival rate for a triple bypass procedure after 15 years at about 50%. In your case, it should be higher because your husband has already passed the initial hurdles i.e. dying on the operating table etc. So it depends entirely on which side of the 50% your husband is - nothing is ever 100%.
I think it might be worth adding that if your husband had bypass surgery 7 years ago, he is one of the lucky ones who tolerates such grafts. It is likely his will be one of the longer surviving especially if he has had no angina symptoms of stents in the grafts in those 7 years.
Ok, here's the truth of the matter. Coronary artery bypass is a procedure which obviously comes with no guarantees. Everyone is different. I have met many people in my various stays at different hospitals, and bypass surgery is a kind of luck of the draw, but has to be done to achieve benefits. I've met people who had bypass failure after days or weeks. Mine lasted just three months. I've met people who have lasted decades. The most common failure, due to being far weaker than arteries, is vein collapse. In many people they simply aren't up to the job. However, in bypass surgery they tend to use an artery from the chest (LIMA) as one of the grafts and this artery is as tough as old boots. It will last the natural life of the patient. Yes it can form blockages, but it can also be stented.
Now, what about death from bypass collapse. This is highly unlikely, I'm still here (at least I hope I am). All that will happen in the worse case scenario is that you will end up the way you was before surgery took place. If you was alive before surgery (very likely), then you will be alive if the bypass failed. When people say "they died ten years after the bypass", it wasn't because of the bypass, failed or not. They very likely had a heart attack. With todays medications this risk is lower than it was many years ago. When my bypass failed, I was breathing VERY heavy for about 2 mins and it settled down. I went to the hospital where they quickly discovered the veins had failed. They put me back on beta blockers and I felt fine. Then my original arteries were opened and stented, which was considered too risky the year I had bypass. So a bypass can fail at any time, and it certainly doesn't mean the end of the line.
I have a friend who recently celebrated his 20th anniversary after bypass surgery.
The type of statement made like that are usually people with an agenda, selling or pushing some 'natural' nostrum. I've heard such things and as a bypass surgery survivor, I try and ignore these ignorant people.