Presumably the speculation is based on the notes for the upcoming maintenance, which for some unknown reason lack a Maintenance Details section.
Notice: Maintenance

Thank you for playing Millennium War Aigis.

Maintenance will be performed on October 31, 2017 (Tue) 3AM.
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Maintenance Period
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October 31, 2017 (Tue) 3AM ~
October 31, 2017 (Tue) 6AM (EST) (Estimated Completion Time)
This doesn't innately mean there is no event however. Even when we've had break weeks in the past, they would still have the section to note the previous event was coming to a close. As such all we can do is speculate about what will happen tomorrow.