Yes of course. Grow the potential gain from mining by having more transactions leaving the fees at current rates.

To be honest, once the average fees per block surpass 50btc - I'd expect that the next logical step make blocks happen faster. With the eventual goal being a block every 2 mins. This would be the final step in making the network robust enough to actually compete with traditional point of sale networks.

Now we could wait for that growth of mining rewards to happen naturally - but there might be a chance that this gets done early, assuming that the network gets into the 2000+ transaction per second range.