What will be the role of eosDAC tokens in the future? And will it be available in a wallet sometime in the future when the EOS mainnet is established?
EOSDAC pitch themselves as "The Community Block Producer". Their tokens represent your stake in the block producer.
It is not yet entirely clear how your EOSDAC ERC20 tokens will transfer to the EOS platform, the EOSDAC website still says that the process will be "defined by the launch team, that will be described on the eosDAC website and social media channels."
Some exchanges, such as OpenLedger have promised to handle the transfer on your behalf. Any ERC20 EOSDAC tokens you hold in OpenLedger will automatically convert to actual EOSDAC. Trusting an exchange comes with risks, so you will have to weigh up the convenience verses control.
Other than that, the FAQ is still a bit vague as to utility: "The initial eosDAC tokens will give rights to have eosDAC tokens on any EOSIO blockchain that the eosDAC launch team supports. Activated EOS accounts with eosDAC tokens will have the rights to participate in the eosDAC activities and gain eosDAC benefits. In due course, it is probable that eosDAC will provide Dapps and utility based services which can be used by members."
However we can speculate. Block Producers will earn the new EOS released onto the network. It is possible that if voted as a Block Producer, EOSDAC will be able to distribute this proportionally to its holders. They also make decisions about the future direction of EOS. EOSDAC tokens will likely allow its holders to vote on the position of any issue that the EOSDAC should take.