will the bonus to miner stop at some point ?
The subsidies are there to compensate until the pool gets big enough to turn a profit and maintain a #1 position as the most profitable pool on our way there. It's the only pool powered by dpos so we can do things most people can't.
Really when it comes down to it, the goal is to increase the market cap and liquidity by having more people moving money in our system.
Once bitsharesmining gets to a point where the added benefits are marginal compared the the marketcap than the operation should stop being subsidized.
Later, when BitShares grow enough of it's marketcap and doesn't value the added liquidity provided by the pool then it will be a good time to realocate those funds to a better purpose.