The decline of pinball had nothing to do with console games. The decline started in the early 80's with the advent of Space Invaders, Galaxian, Asteroids and Pac Man. The rot was well and truly "set in". Console games that came on the scene years later emulated video games, and not pinball. Video games started the decline.
What's my source ? I saw our LAST pinball container opened in 1980 ish - the last pinball container arrived full of NIB Ballys, Gottliebs and Sterns.
The next container that arrived was full of Videos - Space Invaders clones, Pac Mans, Tempest etc etc.. Not ONE pinball.
I do recall in 1984 ish, a container filled with Fathoms, Medusa, Eight Ball Deluxes etc etc was left in the USA and not imported. ANOTHER container of Vids replaced it. That was the start of the end. The 70s-80s was the glory days that the 90's would never see. What the major manufacturers did in the 90's was on a much smaller scale - but nevertheless - this period would be the hardest for them as Videos killed off the pinball industry.
I still remember the days of a dozen solid states in every second Arcade, and then the horrific sight of cocktail tables and upright videos that replaced them. It was very hard for the pinball manufacturers in the 90's. But Williams were definitely still profitable in the late 90's and could have kept going with pinball. But they had shareholders to look after.