Luckily the transaction fee isn't a set limit.
I would guess that it would be adjusted to where the total average number of transactions multiplied by x (transaction fee) / 10 minutes would equal at least half of the current block reward for that time.
There would be a very large volume of transactions at that price.
where do you even get your maths from
currently transaction fee's work out at 5% of the block.. not 50%...
the way things should work is that miners get paid from the reward, EG if 1bitcoin is $100k then the reward alone would be:
12.5btc:$1.25mill to share
6.25=$625k to share
all for just 10 minutes work.
at the moment the reward is $25k-ish per 10 minutes work to share between workers. so as bitcoin increases in price the reward would still be more then enough.
doing transaction fee's to subsidise pay just makes miners not want to hold out for a better deal (increasing price by holding/causing demand increase). we should be in the mind set that if the reward is not enough, then miners would hoard coins for a better price.
if transaction fee's become expensive due to being used as a subsidy, people wont want to use bitcoin. and the price would fall. causing miners to rely on transaction fee's more, causing even more people to not want bitcoin.
i think abolishing transaction fee's until the reward is something like 1.5625btc per 10 minutes. and then still have a 5% cap of total costs. this would incentivise miners not to just sell out at any old price that comes along, but to hoard until the best price comes along.
think about it. if gold miners sold their gold for $10 an ounce, and then were subsidised by government tax, where every trade of gold had a 50% tax on it. would you think gold would remain at its current price and would people want to trade it?..
.. no people would far prefer no taxation on their transactions and allow the gold miners to sell their gold at true cost/value prices. thus keeping the gold price honest and of true value