I think that people who write posts like these have absolutely no knowledge of price to market cap relelation.
They simply shoot a random number they would like their investment to be at - wishfull thinking (I often see this at RPX subreddit where they are calling $1 soon, and ICO price was less than 3 cents.
Vertcoin at $50 would mean market cap of over $2 bln, which would place it at 6th place in front of DASH, NEO, Monero and stuff.
If i remember correctly, when bitcoin was 150 USD, 300 USD, 600 USD and 1'000 USD, the same arguments were used.
You can't really compare number one coin and pioneer of cryptocurrencies with one of 5000+ alternative coins.
There is no limit for BTC market cap because it's one of a kind (mostly because it was first out there, other than that, it has no real use, just like Vertcoin. ETH on the other hand does).