From the wiki:

Today the Bitcoin network is restricted to a sustained rate of 7 tps by some artificial limits. These were put in place to stop people from ballooning the size of the block chain before the network and community was ready for it. Once those limits are lifted, the maximum transaction rate will go up significantly.

So, if this limit is impose, we won't be able to catch up to paypal's 4 million transactions per day for an average of 46 tps.