"therefore other countries will stop respecting Estonian citizenship to maintain selectivity".

This has already happened in St Kitts[1][2]. They sold citezenship with very few non-financial requirements and now other nations have started screening travellers from there more aggressively, requiring visas, etc.

[1]https://en.wikipedia.org/wiki/Saint_Kitts_and_Nevis_passport [2]http://www.npr.org/sections/money/2016/03/02/468953007/episo...