yes, eventually you would not be able to provide everything required for, say, a busy 20 year old.
Seriously, children do eventually need other foods. Some people feel at about 6 months, while others say up to a year of BF exclusively is fine. I haven't heard anyone recommend delaying introduction of solids later. Iron is usually the first thing that they worry about being inadequate. In any case, if you plan to BF exclusively for an extended time, you would want to make sure you had plenty of iron and other nutrients and minerals to give to baby.
As far as studies go, there are studies that show that waiting 6 months means less food related problems like allergies. Of course this is approximate, not an exact thing - if they tested 5 month old babies who knows what they would have found? The last I heard, no one had actually done a study showing benefits to waiting a year - some think there are benefits, but that is not based on any actually studies, so it is really an open question.
But, your baby may actually have other ideas than you. I take a child-led approach on solids and both of my girls started being really interested in food at about 5 months - watching what people ate while making chewing motions, trying to grab at it, and so on. Neither were huge eaters until after their first birthdays, but they really enjoyed trying new foods.