A few thoughts to chew on as you plan your syrah:
Aging time is quite dependent on the aging conditions, the grapes, and the wine-making. Generally, the more tannin in your wine that was extracted from grape skins during fermentation means that it will need to age longer to soften the tannins as it builds structure. Bordeaux wines are typically aged 6+yrs (barrel+bottle) before being considered table-ready while a Rhone Burgundy may be consumed much sooner.
Berry (fruit) wines are usually intended to be fruit-forward and have negligible tannin. Aging them will result in less fruit on the nose as it oxidizes and degraded color stability.
As far as your wine goes, here are some factors to consider. If you ferment on the skins and have a longer maceration, you will extract more tannin and require more aging time. Are you aging in oak or stainless/carboy? The magic of aging is the micro-oxidation that happens through the barrel wood, which can't happen through glass or stainless. Where are you aging it? Higher temperatures will speed up the process.
Aging is primarily about the tannin in the wine, with pH and alcohol being secondary factors. The pH (and your sulfite level) affects how quickly the wine oxidizes. The alcohol can either increase or decrease during barrel aging depending on the temperature and humidity, which is why barrels are aged in cool humid environments.