I would only lose interest if the Lakers go 82-0 and win every game by 40 points, even then I probably wouldn't lose interest until the 2nd or so season of that, though the second somebody has a competitive game/series against them I'd immediately be interested again.
Watching history be made (72-win Bulls, 73-win Warriors) and watching/hoping giants fall (like the 73 win Warriors losing, or the C's ending the Warriors 54 home game winning streak) is always entertaining.
And personally, I'm not sure if the Lakers would be that dominate. In the last 20 years or so, every time a "super team" has come together, the results have always been less than what people expected.
Barkley, Olajuwon, Drexler/Pippen: Lost in conference Finals, then back-to-back first round exits. Over the hill sure, but had high expectations they never met.
Shaq, Kobe, Malone, Payton: People were saying they'd go 82-0, it's not fair, only to get beat in the Finals.
Pierce, Garnett, Allen: even though they won a championship in '08, had two 7-game series that year.
LeBron, Wade, Bosh: people thought they'd steamroll the league. Didn't even win that first year, still won 2 titles out of 4 years. The 2 years they won they had three 7-game series and only 1 sweep in the playoffs. The unstoppable dominance wasn't there.
Durant + Warriors (since the Warriors pre-Durant were an organic creation I won't count them): they pretty much steamrolled the league that first year, only losing 1 playoff game, but that was also due to a Kawhi injury (I like to think that could have been a 7 game series). But in 2018 they had a 7-game series, and in 2019 (after adding Cousins) they didn't even win the title.
Whenever the super teams have come together, they never dominate like people think they will. Opposing teams are still able to challenge them. The NBA will still be entertaining.
Lakers will have to deal with injuries, chemistry, lack-of-depth, LeBron's decline, etc. Even if Kawhi signs, I'm not ready to crown them the 2020 champion just yet.
My interest in non-Celtics basketball would increase a little at first as I'd be interested to see how everything plays out with the Lakers and rooting for them to lose.