The chain is not the problem per-se, it is the plastic guilde rails. With age they will deteriorate and could break with pieces making their way under the chain between it and the cam gear, particularly on the left side. Then you have big, big problems. The guide rails should be changed about every 10 years regardless of mileage. The chain will elongate but almost never break...but to change the rails you do 90% of the work to replace the chain so you might as well do it as it is only $100 extra and you won't have to worry about elongation of it again for another 100K miles.

__________________
Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz