The fact that Arsenal built a new stadium and subsequently regressed doesn’t mean that Spurs will do the same. You need to look at the finer details. For starters, it might just be that Arsenal’s relative decline starting just as they moved to their new stadium was entirely coincidental. Because by then, Wenger was no longer ahead of the curve, as he had been, and in fact became something of an out of touch (albeit football romantic) dinosaur by the end; Abramovich happened; then ADUG; the George Graham stalwarts in defence had all grown old and retired; and the key players who won them that rash of trophies in the late 90’s / early 00’s - Vieira, Bergkamp, Henry and Pires - all left and were never adequately replaced.
But even if we are to say that their stadium build was largely responsible, there are key differences.
When Arsenal began construction, their revenue was £135m. Spurs’ revenue last season, before the new stadium bounce, will have been three times that amount.
Arsenal also took on significant debt for a large property development programme which failed to realise anything like the hoped for profit because of the property crash and credit crunch from 2008. Furthermore, their credit was secured at pre crash interest rates. Spurs’ credit is secured at historically low rates. Arsenal did restructure their debt with a bond offering but still at higher rates than Spurs will have to pay.
Lastly, the vision behind and the versatility of the new Spurs stadium means that it will be a greatly superior income generator than even the Emirates - especially in terms of attracting non football events.
But all of the above, while relevant to your post, isn’t really relevant to the particular issue that was being discussed. No one was claiming that Spurs will now enter a golden era as a consequence of the new stadium. There is no telling whether trophies will be forthcoming or whether we even go the other way and fall out of the CL places. The point about increased revenues was simply to say that Spurs will henceforward be able to further close the wage gap with their competitors.