Voting with your feet / wallet is certainly one option!
My experiences (albeit limited) with KLM were mostly positive and their customer service was very impressive when I was trying to fly from AMS back to the UK for Christmas quite a few years ago. Due to the threat of BA industrial action and a Eurostar weather-related shambles I'd decided that I'd take the train from BRU to AMS and then fly back to NCL from there. Even before I'd arrived in Schiphol it was patently obvious I'd missed my AMS - NCL flight because of weather delays impacting the Thalys. Fortunately I'd booked a flexible business class ticket and so KLM rebooked me without hesitation onto the next day's flight to EDI (as NCL was full). However, when it was cancelled due to snow in EDI / GLA they were able to get me rebooked back onto a NCL service! I got lucky because they had one customer who hadn't checked in and had missed the deadline! The fact that they had dedicated staff handling business class customers clearly helped too as I didn't have to wait in a queue and made a flight that, if I was honest, I really shouldn't have. As a loyalty program I really have no idea whether it would be a good alternative to the BAEC. As others have said most of this depends on your flying patterns and destinations. Connecting via AMS may or may not be better than connecting at LHR.
As for the status extension, I got one to 2022 but my wife who qualified for Gold this year has her status until 2023 - and she delights in telling me she'll be the one guesting me into the lounges!
Is the BAEC worth it anymore? To me, yes - but mainly for lounge access when flying on domestic US itineraries. I am currently taking advantage of generally good pricing for (domestic) First / Business class fares and that coupled with TSA PreCheck negates all of the usual benefits of status. The one big exception is lounge access but, to an extent, that is also covered by my Amex Platinum and Priority Pass card. AS joining OW in March next year is definitely another reason why I think the BAEC is still worth it. I have flights to BRW booked for July so 8 x 40 lots of TP will be something to look forward to (assuming that I class fares credit at 40 TPs)!