Putin has made it clear that he supports Assad and the US has accepted that at least for the short term, it is more important to defeat ISIL, and so it is willing to relent on the immediate removal of Assad. The Saudis and the UK, as well as Turkey will go along with this.
Syria is important to Russia and their continued backing of the Assad regime is their way of showing this. They are there to stay. They, the Russians are aware that thousands of Muslims from the Russian regions have joined up with ISIL and they want to finish them foo in Syria before they return home with their "jihad".
The combined forces of Iran , Hizballah and Russia ( who favor Assad), together with the US-led alliance ( France has also joined in the bombing of ISIL bases), will now co-ordinate their attacks. There is one problem and that is the Syrian rebels fighting Assad forces. There is also Turkey, which wants to take the fight to Kurdish elements in Syria (they are accused of attacks on Turkish troops). This could lead to confusion and mistakes, if there is no cooperation and coordination of efforts.
Ukraine is another matter of concern as Putin has made it quite clear that he will not withdraw his support of the break-away East. Russia has always been paranoid of encirclement, and they are very concern about NATO expansion. They want a stop to it and will do whatever it can to undermine and stop that expansion, whether it be Georgia, Ukraine, Moldava or the Baltic.
In the meantime, the Iran nuclear deal has brought US and Iran closer. They are not friends and they are wary of each other. However, there can be some good, not only for Iran ( with the freeing from the embargo, Iran is open for business and many countries, Britain, France, Germany, China etc. are eager to capitalise), but also with the situation in Iraq, Syria and Yemen, Afghanistan, where Iran has influence and the US need to work with Iran. The Saudis, the Israelis and the Qataris may not like this (even Turkey), but they will have to live with any cooperation between USA and Iran.
In the weeks ahead, it will be interesting to see what, if any, progress is made in these areas. In the meantime, Cuba is well on its way to enjoying the fruits of the recent US openness. Cuba and Iran are two of Pres. Obama's great successes, against severe odds, both at home and abroad.