RE: Conte’s acid test
I did say in my prediction that I wouldn't be surprised if Spurs compete for the Premier League title until the last few weeks. But, much like you, I don't see them winning any of the big two. Although, the UEFA Champions League is one of the most random tournaments so it is possible.
The issue with investing further in this squad is that you could only buy starters now and I don't see many available, and even less so who'd be interested in playing for Spurs.