While the timeline for Bill C-6 cannot be reliably predicted, it is likely it will be adopted and become law.
To the extent the Senate might obstruct adoption of Bill C-6, while technically it could totally scuttle the Bill, the likelihood of that is small. Possible, but not at all likely.
The more salient possibility is that the Senate proposes amendments which require the Bill to be revisited in the House of Commons, and if those amendments are not acceptable to the majority in Parliament, the process could take a long while to reconcile the differences and pass a Bill which gets adopted. The usual suspect would be section 3 in Bill C-6, which repeals subsection 10.(2) in the current Citizenship Act (provision giving Minister authority to revoke citizenship for those convicted of certain crimes), and section 4 in Bill C-6 which amends other provisions of the Citizenship Act related to the implementation of subsection 10.(2).
Whether this particular part of Bill C-6 (sections 3 & 4 of the Bill) becomes problematic may depend in part on the extent to which Canadian opinion swings one way or the other. Currently, as noted before and often, the Liberal motto a Canadian is a Canadian is a Canadian appears to have wide-based and strong appeal, and unless this is dramatically eroded (such as in reaction to a major terrorist event in Canada or directly affecting Canada), it is hard to see how the Senate could successfully oppose these changes to the Citizenship Act.
In any event: While it is difficult to say when, the odds are high that Bill C-6 will be adopted and become law, with no major revisions. However, politics are always prone to dramatic and unpredictable shifts in the wind, so there are no guarantees, none at all. Unless and until Bill C-6 is passed by the Senate and finally adopted in Parliament, there is no relying on its provisions becoming law, let alone on any predictions about when its provisions will take actual effect.