I heard that CBS' budget cuts pretty much killed (https://web.archive.org/web/20061031125322/http://www.jumptheshark.com/k/knotslanding.htm) it (https://moviechat.org/tt0078638/Knots-Landing/58c73a5e6b51e905f66a8e4c/Season-13). It was as if CBS during that last two seasons (https://moviechat.org/tt0078638/Knots-Landing/58c73a5d6b51e905f66a8dd7/Season-9) was deliberately sabotaging it.

Eh - it was out of gas as it. The last couple of seasons were not the best. If they wanted to bring it back for another season, they needed to reboot it: focus on the Mackenzies and the Ewings, with a new set of neighbors. David Jacobs said he pitched that idea to CBS, but they weren’t interested.

1988-1993 were the later seasons of Knots Landing because the storylines are different & the real reason is CBS decided not to renew the show for Season 15 after that.

The quality suffered over the years-period.

If it didn't become too expensive to produce by the time it went off the air in 1993 (https://www.youtube.com/watch?v=G7lLsSMco-k), could Knots Landing have theoretically, lasted at least 20 years? Unlike other primetime soaps of its era such as Dallas, Dynasty, and Falcon Crest, which usually focused on one family or business (an oil company, winery, etc.), didn't Knots Landing (https://tvtropes.org/pmwiki/pmwiki.php/Series/KnotsLanding) frequently change its "hot spots" over the course of its run? In other words, while it always kept the cul-de-sac (https://web.archive.org/web/20140401220025/http://forums.televisionwithoutpity.com/topic/3112863-knots-landing/page-19#entry10999817) at least on the back burner, it none-the-less, still changed directions and evolved over the years.