Yes, some people could indeed still submit applications on the old forms so long as they were received at CPC-Sydney by January 10, 2018 . . . and they were signed no later than October 10, 2017 . . . and signed within 90 days of the date they arrived at and were received in CPC-Sydney.
This is because IRCC's policy for stale-dated applications is 90 days . . . so the last date an application under the previous law could be made (signed) was October 10, 2017 and for that application to not be stale-dated it had to be submitted in time to be received by CPC-Sydney within 90 days of the date it was signed, that is, by January 10, 2018.
Odds are high that there have been very few old applications received in the last month, or even two months (unlike when the last changes took effect, with perhaps very few exceptions, but none that I am aware of, no one who was eligible in October under the old rules would be made ineligible under the October 11, 2017 changes). But for some reason IRCC decided it was necessary to give this notice.
