I don't think there was any particularly clever strategic plan. And sadly I don't think any Ukrainian counter-offensive is going to make any particular difference.
Ukraine is the new Syria, the conflict will probably never end.
Western-backed forces in Syria never really got started, nor was there much interest from the West in doing more than a bit of fighting - against ISIS, which was also engaged in Syria.
However, you're right that this is going to be a long war. At least as long as it has been going on already. And then it will probably turn into a frozen conflict like North/South Korea or "Turkish" Cyprus.
Ukraine is the new Syria, the conflict will probably never end.