At best you should expect to receive 25% of your balance, and that will take a long time to materialize. I would put a max value of the above rate. However the fact that it could take years for the bankruptcy process to finalize, the exact formula as to how creditors will be repaid, and uncertainty regarding if the transfer of liabilities will be recognized by the court would greatly reduce the value.
Seems to be more like 20%:
The chances to get something back are very good, provided that 1) you establish your claim and 2) your claim amount isn't really small (for claims below JPY1,000, the trustee has said that you will still get the payout, but you might have to come pick up your money - not practical for most people).
We don't know the percentage and it will depend on undetermined factors, such as how many people decide to make their claim. Some have speculated that it might be around 20% based on some public information, but it isn't certain.
All currencies including BTC will be considered in terms of their value in JPY when MtGox went bankrupt. These values will be used to determine your pro rata share of the total remaining assets. If you request a payout in BTC, the amount of BTC you receive would be your pro rata share of JPY converted to BTC at the current market rates.