Apple rumours are a funny business; for every spot-on bit of uncovering done on a company that wears its secrecy as a distinct badge of pride, there's an avalanche of wild guesses, half-baked theories and distractions to deal with. One rumour that's doing the rounds right now with a fair amount of regularity is that the next-generation iPhone will feature a smaller 19-pin dock connector, rather than the 30-pin standard connector that Apple's used since 2003.
In this case, even if the rumours are on the money, this won't necessarily invalidate the plethora of docks, connectors, batteries and other devices that use the 30-pin dock. iMore reports that Apple will most likely provide an adaptor with the new iPhone, although it's unclear if this will be as a provided accessory or something that you've got to buy separately. There's some history here to suggest that Apple might do just that; in order to get around an EU edict that stated that all smartphones had to standardise on a connector to save on charger waste, Apple ships European iPhones with a microUSB to 30-pin dock converter.
Even if Apple has no such plans, if the 19-pin connector is a reality, expect converters to flow out of Chinese factories and onto eBay within minutes of the official announcement of the next iPhone, now widely rumoured to be in August. The only downside with an adaptor would be that it might not fit every accessory; some battery cases notably might not have the space.