こそすれ〜ない

Occasionally in Japanese, the adverbial particle こそ will be seen followed by the realis form (sometimes referred to as the perfective form) of verbs. This is a classical verb form that does not have a modern counterpart. However, the hypothetical form has largely replaced the realis form in the manner in conjugates.
The verbs that will be seen altered this way are する ‘to do’, なる ‘to become’, and ある ‘to be’. They will respectively become こそすれ, こそなれ, and こそあれ , and are used specifically for emphasis. Common translations include ‘certainly not (B), but (A)’, or ‘even though (B), actually (A)’. The (B) phrase in this grammar point will include a negative statement, and is usually something that the speaker is responding to or correcting about what another person mistakenly thought.
こそすれ may attach to either the noun part of する-Verbs, or the conjunctive form of standard verbs.

• このままだと日本(にほん)の経済(けいざい)は悪化(あっか)こそすれ、回復(かいふく)はしないだろう。
  At this rate, Japan's economy will continue to worsen, and certainly not recover.
• あのカードは世界(せかい)に一枚(いちまい)しかないので値段(ねだん)が上(あ)がりこそすれ、下(さ)がりはしないだろう。
  That is the only card that exists in this world, so the price will keep rising, and certainly not decrease.

なれ and あれ will be used based on the standard rules of what type of word なる would usually appear with (a noun or adjective), and what type of word ある would usually appear with (a noun).

• 運動(うんどう)は健康(けんこう)のためにこそなれ、絶対(ぜったい)に損(そん)にはならない。
  Exercise will be beneficial for your health, and you certainly won’t regret it.
• それは損(そん)にこそなれ、利益(りえき)になることはないだろう。
  That would be a loss, and certainly won’t be profitable.
• 憎(にくし)みこそあれ、実際(じっさい)に傷(きず)つけようとは思(おも)ったこともない。
  I have felt hatred towards you, but I certainly have never thought of actually hurting you.
• 彼(かれ)はコミュニケーションの能力(のうりょく)こそあれ、仕事(しごと)は得意(とくい)ではない。
  He has skill in communication, but he certainly is not a skilled worker.