Umtiti ticks all the boxes of a Pochettino-style signing: young, talented, ambitious, and probably relatively inexpensive, with reports suggesting he might cost as little as €15m. He's a ball-playing central defender who can also fill in at left back as needed. He was a regular in Lyon's back line, both in League 1 and in the Champions League, and has even scored once this season. That's good!
It's not impossible that Spurs might consider making another depth signing to prepare for the rigors of Champions League and Premier League competition. Umtiti would certainly compete for minutes, though he'd be joining a crowded Spurs central defense. It's unlikely that any player would break up the "Belgian bro" partnership of Jan Vertonghen and Toby Alderweireld, and any newcomer would be competing with Kevin Wimmer and possibly Cameron Carter-Vickers or Dominic Ball (assuming he's not converted, Eric Dier-style, into a defensive midfielder).
He's also reportedly on the radar of Barcelona, which is probably not so good if you're Spurs, and there's also the fact that Lyon is very likely to make the Champions League this season, so it's not just a matter of promising him UCL football.
I wouldn't hate this if it happens. While Kevin Wimmer filled in ably for Vertonghen during his injury, we were probably pretty lucky that Toby's legs didn't fall off while we were playing him in every match this season. Another solid defender would create a true rotation, which would be needed if Carter-Vickers or Ball aren't ready for prime-time.
But of course, this is the beginning of Silly Season, and this report from L'Equipe is short on anything resembling "facts" or "quotes" or "evidence." Spurs are going to be linked to just about anyone under 25 and decent. I wouldn't put much stock in this rumor yet, but it sounds like it could be a pretty good deal.