Would Interactive Democracy (ID) mean the ultimate demise of political parties?
There is a role for them in ID, to put forward the best candidates to become MPs, to debate political issues, create ideas for improvement and to solve national problems, to put forward theses ideas in the ePetition (Ideas Engine) system and to vote together en-mass to effect Interactive ballots. Also, people who want to be in government are likely to need to belong to a political party - the winning party in a general election. So, there are still very good reasons for parties to continue to exist.
In ID the power of political parties may be somewhat diluted among the population as a whole, as everyone can vote on each issue. However, this means that individual party members actually have more power, both as party members and normal voters. Their leaders have less power except for their powers of persuasion.
The Political Parties could also use the Interactive Democracy infrastructure for internal polls, perhaps improving the efficiency of there own operations.