That's certainly an interesting way of doing things. Surprisingly not too far off the mark either for just multiplying the original roster by "x" based on what number game it is.
The way I've tried to predict the roster total, is by comparing newcomer additions and cuts. And just to make note of it right of away, it's extremely flawed and I'm not making an actual prediction or claiming it to be accurate. Just putting it out there for fun.
Melee; 14 newcomers - 0 cuts = total increase of 14
Brawl; 18 newcomers - 5 cuts = total increase of 13
3DS/Wii U; 17 newcomers + 1 previously cut veteran - 6 cuts = total increase of 12
DLC is not counted as that is content developed apart from the base roster under different circumstances, and the guess is of course, supposed to be for the base roster.
Based on the above, the average would be an additional 13 characters per game. Alternatively, if you really want to count the original Smash Bros. cast, the average is 12.75 which you can pretty much round up to 13 anyway. Or maybe round it down to 12 if you want to play things as safe as possible given how massive the roster has gotten.
Average newcomer additions = 16
Average character cuts = 3 to 4, which I'd personally round down to 3 despite being 3.66~ so as to match up with the average character gain of 13. Though 4 cuts still works if you rounded the 12.75 to 12 to play it safe.
Not doing an average on previously cut returning veterans as
is an outlier and the others were DLC.
Aside from that, if you want to try to predict how many of newcomers will be clones there were
1 in Super Smash Bros.
6 in Melee
1 in Brawl; Not going to get into a whole clone argument, but I'm only counting
as he is the most similar to the character he was based on.
and
reuse a lot of assets, with the latter borrowing the most heavily, but both in totality are very different. They share similar specials, but the vast majority of their tilts, smash attacks, aerials and throws are different.
2 in 3DS/Wii U
Newcomer clone average = 2 to 3
So based on all of the above a possible prediction would look like this:
Super Smash Bros. Switch
-Roster total of 64 (Smash 64 I guess?
)
-16 newcomers, including 2 to 3 clones
-3 characters from 3DS/Wii U do not return
Now as mentioned before, this doesn't account for DLC characters, so the base roster could be bigger depending on which ones return. And of course the grand total would be even larger depending on how much DLC of it's own a new Smash gets.
Also as mentioned above there are of course numerous flaws, many of which are simply on things we can never account for without intimate knowledge of development circumstances which has been vastly different for each game either way, making attempts at finding patterns mostly fruitless.
For all we know, they could more or less reboot Smash and start fresh from zero, in which case a possible roster could fall back down into the 20s or 30s