30 is pretty much guaranteed. Here's where I'm at right now.

Will be getting my own Wii U and X1 in the next couple of months, so I'll have some more balanced representation.

Anywhere from 20 - 40 probably the lower end though.

Depends on the console, like I buy way less for Nintendo consoles just cause they have less games and the most for the console that plays multiplatform games the best.  Last gen it was Wii 20-30, 360 100ish, ps3 50-60.

N64: 12
GBC: about 10
PS1: about 10
PS2: about 15
GC: about 20
GBA: about 20
Wii: about 30
DS: about 30 (about half of which are Pokemon)
3DS: 19
Wii U: 11
PS4: 1

so the average of that U:

Out of all the announced games, on the 3DS I'll have around 25, Wii U around 35 and PS4 is about 38. (If I got all of them)

My current collection, in decending order:

NES: 464 (incuding variants)
SNES: 100
N64: 75
A2600: 60
INTV: 59
PS2: 37
GCN: 34
Wii: 29
C64: 27
PS1: 25
DS: 24
GEN: 20
X360: 20
GBA: 19
GB: 17
A5200: 17
VB: 16
SMS: 15
GG: 11
XB: 11
Wii U: 9
3DS: 8
DC: 7
XBLA: 7
Wii Ware: 6
PSP: 5
PS3: 5
X360 (digital): 4
TG16: 4
PC: 4
DSi Ware: 3
3DS eShop: 3
GBC: 2
SAT: 2
TCD: 2
JAG: 2
PSN (PS3): 1
PSN (PS1): 1
A7800: 1

An Average of about 8-12

Including digital titles, probably over 50 for my main console.
It would be easy to figure out If this site still had its game database...

Around 50 games per console.

Only physical or including digital?

If only physical, up to 30-40. Including digital, it can reach over 100.