As mentioned in a previous post there's a group of people trying to speed up the new gTLD process. They suggest that applicants should express an interest in applying so that ICANN will get a better understanding of the so called overarching issues.
ICANN is now seeking input and advice in this matter. In my opinion it seems like a political multi stakeholder move from ICANN rather than a sincere wish to start a process and a procedure for such a "pre application round". A procedure and process that should be coordinated with the ongoing work on DAG4.
In my opinion it will also be quite difficult to create such a pre application round and thereby exclude applicants that will not apply before having seen final guidebook - and if new applicants that didn't sign up and deposit money in the pre application round are not excluded, it will be hard to see the relevance of any pre application.