The only thing that will keep it going is if goods and services are traded in bitcoins. Mining alone is worthless without people willing to purchase bitcoins.
You're right. What most people don't get is that we have more than enough people to maintain the system at the moment. What we need is to stop telling people to start mining or we all make less money. If we tell people that there's an awesome new currency with no fees and no stupid legal BS to jump through that anyone in any country can use with no overhead fees and they should try using it instead of paypal in their next purchase if applicable, then we'd all make money cuz there would be a higher volume of people buying into the currency.