Let's suppose we have imported 300 units of latest version of SU35. Let's again suppose we defeated F-22, F-18, F-16, F-15, French Rafales, British Eurofighters and Typhoons over Jordan, Iraq and Syria.
How are you going to pass through patriots, THAAD plus Israeli, German gifted, European gifted Air defense systems in Israel?
Fighter jets are good to defend skies and also monitoring airspace to avoid being surprised. Problem is that the opponent uses stealth technology.
Until we don't have a stealth jet fully built locally, we cannot waste resources on Russian inferior jets. Not even Chinese jets can help us in this case. China won't sell J-20 or 35. So forget about imports.
We need a local 5th generation jet which can be manufactured at will. And it takes time.