I doubt that, because the drop occurred as soon as Lineker left the show, and even if it was a more gradual reduction, then you'd have to balance that off against the fact that as young people grow up and become more invested in football they'll naturally become new MOTD viewers and replace the old.
Remember, Lineker's removal from the BBC wasn't just a graceful retirement or moving on to pastures new, he made some observations about a geopolitical situation many people feel strongly about, and the BBC's response to that was to censor him and remind him BBC employees can not be seen to be impartial. So this can't really just be viewed in the context of MOTD alone, because Lineker's statements, the BBC's response to it, and Lineker leaving the channel will all undoubtedly have had the effect of more and more people losing confidence and/or interest in the BBC itself.
My personal biggest gripe with the BBC is it doesn't even understand the "impartiality" it consistently brandishes as it's main selling point. The BBC's mangled sense of "impartiality" means that it never challenges anything for fear of being seen as partial, and this includes journalists sitting back and permitting known liars to openly lie using the BBC as a medium to propagate those lies. Proper journalists look out of the window if someone tells them it's raining, the BBC just dutifully reports that a "source" (another bugbear. If your source is unwilling to be named, then they aren't remotely credible) has told them its raining and unquestioningly repeats this as news.
This is true whether the matter at hand is originating from the perceived Left or Right of politics, which is precisely why people of all political persuasions now consider the BBC to be biased, skewed, incapable of objectivity, and uninterested in truth, hence why you see people accuse the BBC of "antisemitism" despite rolling news coverage of perceived antisemitic attacks which isn't afforded to attacks on other ethnicities, and the fact they'll platform Tzipi Hotovely repeatedly, and allow her to sit and spew Likud and Israeli State propaganda while never challenging her over any of the blatant untruths coming out of her mouth, or asking her about any of the Israeli States myriad of crimes against humanity, their flagrant, long-standing disregard for International Law etc.
Nobody trusts the BBC anymore, and it's entirely their own fault. The reason I will not pay a licence fee under any circumstance is that I'm in Scotland, and their regional news output up here is so blatantly biased that they've recently taken to passing off confected Tabloid newspaper shit as news rather than reporting fact. It's baffling that the regional independent, STV, itself a tinpot outfit, still manages to put out far more even-handed content and displays a journalistic integrity BBC Scotland entirely lacks. I refuse to pay for State Propaganda presented by shills masquerading as an "impartial" news service.