You had a number of questions in there.
To go back to the first point, the declaration of use form does not signify all of the elements of use that are in the Trade-marks Act. Therefore, getting rid of a single form does not mean that use is not part of the act anymore.
For example, section 30(1) of the act, clause 339 of the bill, says:
A person may file with the Registrar an application for the registration of a trademark in respect of goods or services if they are using or propose to use, and are entitled to use....
It is the core grounds of use.
In terms of opposition, which is the point at which people can challenge the granting of a new trademark, the applicant can bring forward a challenge, an application on the grounds that it's not being used and that there's no intention to use. This is in clause 343 of the bill.