I found that absynth 5 was deleted in the latest komplete 14. Does it mean that after I upgrade to komplete 14 ultimate, the synthesizer I once owned will be invalid forever?
You're not losing anything by upgrading to Komplete 14 (or any version for that matter). Upgrades / updates just add products, not take away the ones you already own. Absynth 5 will still be available to you.
In addition, the price of komplete 14 CE has increased from $1599 to $1799.
You'll also find some answers in this thread.