Are Wii U games and classic games the only way to avoid M's?

It's awful! Video games are becoming only for adults! I'm 24, I have a niece and nephew and everytime they saw me playing an M they would ask I said no and they cried so I don't play M games anymore nor am I allowed to anymore, the video game industry is even losing money, there will not be anymore video games being made anymor if the stupid M keeps up! The only options to stay away from M's are either Wii U games or classic ones. "Video games are becoming only for adults"
No, they aren't.

Numerically, there are more T(een) games than any other rating.

Even sticking with E/E10 there's still plenty to play, even on the Playstation and Xbox:
Sports games - Madden, FIFA, etc
Racing games - Forza (Xbox), Gran Turismo (Playstation)
LEGO games - too many to list here
Disney Infinity / Skylanders / LEGO Portal (as usual, Nintendo is late to this party too)
Minecraft / Terraria
Platformers - Banjo Kazooie Nuts & Bolts (Xbox), Ratchet & Clank (Playstation)

If you throw in Teen games you get:
RPGs - Blue Dragon(Xbox), Final Fantasy XIII (both), Final Fantasy X/X-2(Playstation), Disgaea(Playstation), Eternal Sonata(both), Fable (Xbox), Star Ocean (both), Rune Factory (Playstation), Kingdom Hearts (Playstation) (most Japanese RPGs are rated T)
Fighters - Street Fighter (both), Blaz Blue (Playstation),

Are there a lot of M games? Yes.
Is that all there's to play? No.
Are the best games only rated M? No.

"the video game industry is even losing money"
No, it's not. Profits are up across the board for just about every publisher and platform - even Nintendo.