If you take care of the boat, it should last some 20 yrs. My 85 Jeanneau is still going after that amount of time. Granted when I bought the boat 5 or so yrs ago, while I do not want to say it was beat up it was not, but we have done a complete redo, ie cushions, varnish, liner on the hull and ceiling area's etc. If you used a boat alot, no matter the brand, even an Oyster, I would suspect many of the items I replaced, would need replacing on them too!
Otherwise, if the boat suits your needs, go for it, if you want a smaller unit, look at the 379, a semi pseudo replacement for the 36i at some point in time, altho Jeanneau says it is not a full replacement. Links to the 379 info
Sailboat Jeanneau Sun Odyssey 379 - Jeanneau Yard
Sun Odyssey 379