Most of Russia's trade is not with China & India. The EU takes about half of Russia's exports, & a much higher proportion of its oil & gas. Oil & gas can't suddenly be diverted, especially not gas. There are physical limits to transport routes.I already know the information you stated above.The real production costs of the Western Siberian oilfields is key to this situation. About 90 % of Russia's economic problems is due to the low price of crude oil. China and India will keep making deals with defaulting Russia corporations. Russia has many cards before it will face economic collapse.
Low oil prices are a major factor, but nowhere near 90%. If the economy was better-run it could weather a temporary drop in oil prices. It was heading for trouble even before the events of the past year.
A sensible government wouldn't pick fights with its biggest trading partners just as its economic options were running out - & that's what Putin did, & the situation Russia was in, before the oil price slumped so low.
BTW, Russian firms have huge assets abroad, mostly in Europe - EU countries & Switzerland mostly, I think. Many of them prefer to keep their cash outside Russia, probably because they don't trust Putin & his mates, & they have also invested in foreign firms. The total of such assets is much greater than foreign investments in Russia. Defaults on debts would lead to any such assets owned by defaulting firms being seized. If the Russian state started sequestering foreign assets in Russia, or defaulted on debts - well, a lot of Russian assets abroad are owned by the Russian state. It's put foreign currency reserves into foreign investments.