I saw a post recently where one block had over 200 BTC in TX fees. That should be EVERY block, and it would be if BTC were a mainstream currency. Then you wouldn't be worrying about short term ROI, as every block would be significantly more powerful than simply it's block reward.
You are exaggerating.
Wider utilization of the Bitcoin Network is not a factor to predict increase/decrease in the volume or price of the transaction fees.
You think that transaction fees should generate 200 BTC because you are assuming the case you saw was a result of ordinary collected fees. That is not true and the average fees generated by a block are less than the reward of 25 BTC.
E.g.
If 200 BTC had been generated by only minimum transaction fee, that would mean:
200 / 0.00050000 = 400,000 transactions
Assuming that a block is generated in average each 10 minutes (600 seconds), that would result in:
400,000 / 600 = 666.6...
In other words, you are assuming the Bitcoin Network had a block which was generated by 666.6... transactions per second.
This is absurd.
At the present moment, 12:47 GMT +0, the Bitcoin Network processed 57,155 transactions in the last 24 hours. That means 0.66 transactions per second:
57,155 / 86,400 = 0.6615162037...
Step down of your soapbox and rethink about your hypothesis, because you are not providing a good background for your claim. You forgot to consider that 200 BTC transaction fee could be the result of a mistake:
https://blockchain.info/tx/b18abce37b48a5f434f108ae7ce34f22aa2bfbd9eb9310314029e4b9e3c7cf95http://www.reddit.com/r/Bitcoin/comments/1lb5my/asicminer_refunds_the_accidental_200_btc/ASICMiner refunds the accidental 200 BTC transaction fee. Friedcat is a true hero of the Bitcoin community
Oh, I freely admit that it was a fluke (the one I saw was not the ASIC miner thing, I do remember that.) But to say it's unreachable to have 600+ transactions in a ten minute period? I must severely disagree! How many dollar transactions do you think happen in ten minutes? Personally, I have no idea, but I do know that it's several orders of magnitude higher than that.
This is what I'm trying to say. If we can find a way to take BTC mainstream, that 200 BTC/block would be a LOW average.