We see a lot of people here with many, many cards. We don't normally see situations where lenders think there are too many in total. But we frequently see situations where lenders feel that there were too many that were opened recently.
As far as closing cards goes, FICO likes it when people have three open cards, and some feel that five is even better. If you're under those numbers, close cards if they have an annual fee that's doing you no good and that you can't get rid of. Or you can close if dealing with that particular bank or card is a pain in the butt.
Otherwise, try to hang onto your current cards for the time being. As mentioned, account age stats are unlikely to be affected until down the road, and hopefully by then, you have replacement cards in hand to pick up the slack. Rather than age, the thing to consider is that the number/percentage of cards reporting positive balances is part of scoring. FICO likes to see over half of your cards reporting balances of zero. That's impossible to achieve with one or two cards.
As far as diversification goes, I agree that it's a good idea. But it's not so important that one has to make it an immediate goal. It can happen over time.
