Any indication on how many?
Looking forward to it.
Don't know how many new Su-35S would they order, but initial contract for 48 examples is coming to a completion . therefore, we could expect new order in next couple of months .
Anyway, about that change in strategy concerning PAK FA and some other fighters :
As we all know , Russia has limited funds, and Putin is not entirely too kin to repeat USSR mistake of spending up to 50% of GDP on weapons. Instead, he is preparing for long political battle against West, especially US . Considering air defense and air combat in particular , apparently, Russia has come to following conclusions : Fifth generation fighters are marketing ploys . There won't be many of them in the West , in fact for foreseeable future you could expect just two : F-35 and F-22 .
Russian consider F-22 to be a rare bird and hangar queen (high maintenance aircraft) . They do not expect to see them in raids deep in Russian territory, and even if that happens they are confident that current and future air defense network (S-300, S-400, S-500 in future , modernized Mig-31 ) could defeat them .
As for F-35 , they are quite confident that Su-35 and Su-30SM would be enough to defeat them, at least in defensive fight .Key would be to have adequate quantity . Therefore, instead of building PAK FA as a backbone of future fleet , they would continue to rely on Flankers (and possibly Mig-35) . PAK FA would be specialized aircraft , produced in smaller quantities in next decade (up to 2025) and only after that it would possibly become more common (depending on circumstances , of course) .
Also, stealth bombers (PAK DA) would be developed in parallel with high-speed bombers (modernized Tu-160) , also in smaller quantities then initially expected .
Overall, Russia would not attempt to parallel military development in the West by their own products (carrier vs carrier , UAV vs UAV, fighter vs fighter etc ... ) Instead, they would try asymmetric approach, similar to Chinese posture in 80's and 90's in order to secure their own borders and zone of influence, but not to break the bank .