Are there enough Ripples for everyone?
XRP can be divided into millionths. The reserve levels can be changed by consensus. By the time this becomes an actual issue, the system will be managed by consensus and there's no way to predict what stakeholders will decide to do. The rough expectation is that they'll try to keep the cost of opening an account consistent with the actual cost imposed on the network by having an additional account.

Also, just to point it out again, those 200 XRP aren't lost. You can use them to fund transactions. You just can't transfer or exchange them. The reserve is designed to discourage ledger spamming.