Depends. How long have you been trading YM?
If it's been over 6 months you should have noticed that YM has already migrated from the CBOT platform over to trading on the CME Globex.
Likewise, the depth of market for trading YM has been reduced from 10 bid and 10 ask (or 15x15 on some brokers, like Open E Cry) to the Globex standard of 5 bid and 5 ask only.
Additionally, the start time for RTH (regular trading hours) in the pit for the Dow (not to mention the YM.D start time) was changed from 8:20 am EST to match the RTH for the other indices (like the S&P) at 9:30 am EST, when the (cash) stock market opens.
In other words, it's already happened
-fs