Having only 1 forward (last season) was insanity too. But it worked.
It did, but only through great luck. One twist of an ankle or a knee to Kane probably would have made the difference between Spurs' title challenge and falling out of the top 4 entirely. Their experiments with Nacer Chadli leading the line in cupcake Europa League games were not pretty.
There is Cameron Carter-Vickers as a 4th CB who is supposedly a good prospect (and an American passport holder!), but he's 18 and has literally never played in a first team professional match. Not sure he's ever even been in the matchday squad. And Dier could play there too in a pinch I suppose.
My rule of thumb is always that a team playing in the Champions League should have two full squads of players that you're confident in. Wanyama, Janssen, and Sissoko fill three of those trouble spots. I'm not so sure about the mystery 4th CB or whoever would be the Eriksen replacement (Josh Onomah? Tom Carroll?)
These are certainly first world problems for a Spurs fan who remembers well the days of Pascal Chimbonda and Steed Malbranque being first team regulars, to name a few, but still.