I don’t know if any expert has commented on it,the Sino Russian gas deal for $400 billion has security implications for India. Russia is being increasingly isolated by the west including talks of reduction of energy purchase by the Europeans.This probably led to Putin stitching up the 30 years $400 billion gas deal with China. China probably has got a great deal but will also use this deal to exact price out of Russia and make it back China on various international issues. Russia will get increasingly dependent on China for to provide it with money it needs through oil and gas sales and China knows that Russia is heavily dependent on it.
This has a security implication for India. With India dependent on Russia for weapons,China could play dirty tricks here. Its good that India has already started expanding its sources for weapons imports. . In my opinion, China had a role to play in getting the Russians to lift its arms embargo on Pakistan. News of Mi 35 helicopter gunships being sold to Pakistan by Russia is already out as also is the sale of Mi26 heavy lift helicopter. Pakistan also has given Russia a wish list of arms that includes S 300 SAM system.
China could push Russia to provide it with more weapons. Russia being wary of China stealing its tech to make its own weapons had cut down weapons sales but as seen from the Su35 deal which has now reached 100 pieces that Russia will give China, its likely that Russia will sell more of these weapons to China to keep its defence industry running and provide it hard cash in the face of increasingly isolation from the West.
China could also push Russia to adopt a more negative stance against India in the international fora. Russia might oblige as it sees India get closer to the US and its allies in India. India could well end up against Russia-China combine with India allied with East Asian countries backed by the US.