I have wondered that for years. My personal research has confirmed….yes. And why you may ask? Well over the past 6 years I have aged a number of beers. The Gouden Carolus Noel, for 6 years, in a 750ml version exhibited aging characteristics similar to old Port. The “fruit” element of the beer has fallen off dramatically, and the sugar/sweet element even more so, however, the hops, and some of the added flavoring elements (which are normally added to Belgian Beer…especially the Noels-or Christmas Beers) do remain in various amounts. And the polish….is amazing….so smooth….so lean–due to the lack of sugars–so different from the original, yet compelling. You may ask, what happened to the sugars? Typical of many Belgian Beers, when bottling, they add some live yeast. This yeast, feeds on the sugars, and keeps the beer fresh even after years of aging. After time, the yeast eats up most, if not nearly all of the sugars.
Most of the time I say a beer needs to be 8% or higher ABV for aging. Now I change my opinion, I opened up a 6.7% ABV Grotten Brown Ale (Belgian) that was 4 yrs old. Normally, I would say its over the hill. Nope….there were sufficient sugars originally for the yeast to feed on (creating more ABV) allowing it to stay fresh and remain alive. If the beer doesn’t have active yeasts and have sufficient sugars for the yeast to feed on…then yes a 10%+ ABV would be better for aging over 2 years, however if it does have yeasts and sugars, I would venture to say 6%+ ABV would work also.