The so-called cease fire brokered by some guy who fought in Nam basically divides eastern Syria to Raqqa to US control, and every thing west to Russia along the Syrian Turkish border.
So turkey will either have to cross into the Russian or the US sphere to attack the various parts under Kurd control. The US: no sweat - Russia: WW III or at least the end of the Turkish mil as a fighting force.
With US control of Raqqa, ISIS can breathe a sigh of relief and get back to business killing innocents.
Turkey's military is not a push over. They are several times stronger/well equipped than ISIS, Hamas, Syrian rebels combined.
Turkey entering Syria would be a really bad thing. Russians battling Turks would lead to a greatly expanded war in the middle east.