French Riviera to Italian Riveria in October

I visited Camogli last May and it was delightful. Up to you whether you would find it a good use of your time to go back and forth, however.

I wonder what effect the collapsed bridge in Genoa is having on travel between these two regions?

I think it sort of depends on where you want to go. Genoa itself is 3 to 3-1/2 hours from Nice. Going beyond Genoa to a small coastal town would probably mean some sort of layover in Genoa and then time on a slow regional train. I'd question the advisability of that if you're only talking about 1 or 2 nights. I'd add additional Provencal or Riviera destinations instead, unless you want to stick to the area quite close to the border.

I agree that is along way to go and return just for 2 nights.

I know the road is closed due to bridge collapse so we would take the train.

The bridge fell onto the railway line. Are you sure that the train is operating where you want it to go, and with a reasonable journey time?

1 night I would not do it.
2 nights I would if it is somewhere you want to see or see again.

Don't know the frequency of the train but since parking is tough in most areas you would like go in the Italian Riviera probably best without a car.
I did a similar drive recently though and the drive itself is fairly easy ; (all highway) and only 3 hours or a little over; I am certain there are open roadways to get around the one bridge that collapsed.

I will say the road is far less scenic than one would think ; sea views are rare and tunnels make up most of the way.

The Riviera Ponente, the area of the Italian Riviera WEST of Genoa, is a wonderful, rather laid back stretch of sandy beaches and foothills that slope down to the northern coast of the Mediterranean Sea. Driving the route illustrates the mountainous terrain, as there is a tunnel roughly every 40 feet or so. Sometimes, in places like Alassio, there is more beach than hill. I think that for amenities, San Remo is probably the largest resort town. I stayed in the tiny hamlet of San Bartolomeo al Mare, which is contiguous to Cervo, and had a wonderful time. In October, there may be a number of closed hotels and other businesses, as the weather is getting cooler then. Lots of German tourists inundate this area in the Summer, so the menus and signs reflect that.

So, it is definitely doable, and not so crazy. I think I would prefer a Summer visit.

The train service from Ventimiglia to Genoa has resumed service, according to reports. Obviously the road traffic has been greatly impacted. I have not seen the spillover impact to the rail traffic. You could definitely stay in the Italian Riviera, or do a day trip from Nice to places like San Remo or smaller resort towns like Bordighera. (but I don't know how it is in October).