Yes polkadot future is very bright.
You can't tell for sure, although polkadot is one of the best coin to invest, reason been that is well known and many investors like using polkadot to invest, and a lot of people are also profiting from polkadot.but I can't guarantee you that polkadot has a brighter future, reason is because I don't invest on polkadot, i still want to make a proper research about polkadot before I can give any guarantee.