I read this article about Happy days reboots too!
'Happy Days' Reboot: 10 Actors Who Will Make Fans Say 'Ayyyyyy'
1. Zachary Gordon (Charles "Chachi" Arcola)
The star of the Diary of a Wimpy Kid films is a great choice to play Fonzie's cute cousin that tries to woo Joanie. Zachary Gordon possesses the same type of charm that the original actor brought to the table, a must have for this role.
2. Gedde Watanabe (Arnold)
The owner of Arnold's Drive-In wasn't really named Arnold. He bought the drive-in and kept the name, rather than change it to his real Japanese name. He liked to pop in on occasion and contribute to the antics, much like Gedde Watanabe did in the ‘80s classic movie, Sixteen Candles. After his hilarious portrayal of houseguest Long Duck Dong, he is more than prepared to tackle this role.
3. Bryce Dallas Howard (Pinky Tuscadero)
Happy Days fans will understand this nod to the original series. Richie's real-life daughter would be great as the red-headed racecar driving beauty who steals Fonzie's heart. With roles in The Help, Jurassic World, and a host of other movies, Bryce Dallas Howard has proved that she can play almost any role. Plus, she’s absolutely gorgeous!
4. Mike O'Malley (Howard Cunningham)
After portraying Kurt Hummel's dad on Glee, Mike O'Malley is ready to take on the firm but understanding Howard Cunningham. Both dads, though it might not initially seem that way, always have the best interest of their children in mind.
5. Lisa Kudrow (Marian Cunningham)
Like Lisa Kudrow's character Phoebe on Friends, Marian is ditzy but has a heart of gold. Kudrow has definitely graduated from a friend to a mom, so she is a perfect fit for this flighty and naïve character.
6. Brianna Hildebrand (Joanie Cunningham)
Joanie was the ultimate annoying little sister. Who better to reek havoc on Richie than Briana Hildebrand. Her breakout role as Negasonic Teenage Warhead in Deadpool proves that she has the attitude to portray sassy Joanie.
7. Michael Cera (Ralph Malph)
Ralph is something of an amateur comedian and always has a joke or gag for the group. Michael Cera's experience in movies like Juno and Superbad more than qualify him for the role of Ralph.
8. Graham Phillips (Warren "Potsie" Weber)
Best known as Alicia's super-smart and endearing son on The Good Wife, Graham Phillips would make a great Potsie. Phillips is also an accomplished singer, a must if he wants to woo Happy Days fans.
9. Lucas Till (Richie Cunningham)
Fans feel like they grew up with Ron Howard, so his reboot equivalent has big shoes to fill. Lucas Till of X-Men: First Class and X-Men: Apocalypse has the clean cut looks to portray Richie, the ultimate boy next door. Plus, he's certainly "Opie enough" to satisfy fans of Ron Howard.
10. Skylar Astin (Arthur "The Fonz" Fonzarelli)
After being part of the over-the-top ensembles of Pitch Perfect and Pitch Perfect 2 , Skylar Astin is destined to break out as a leading man (just like Henry Winkler became a break-out star after beginning in a supporting role on Happy Days). Astin is also a New Yorker like Winkler, making him all the more perfect for this role.