The only one thing what is better when you use ERC-20 tokens is that it is really easy to use it, you dont need to have hundreds of diffrent wallets.
Agree. ERC-20 tokens have a greater advantage over most cryptocurrencies with their own independent blockchain. They can be used on any ERC-20 compatible wallet, which eliminates the need to have several wallets for different tokens. With a single wallet, you'll be able to interact with an specific ERC-20 token on the fly. That's why, I believe that tokens have a greater chance of replacing cryptocurrencies over the long term.
I don't think tokens are going to replace cryptocurrencies. Yes, they will probably take a big portion of market cap but many of them are going to have their mainnet and then they're changed to cryptocurrencies themselves.
That's certainly true, mate. Many tokens have switched to their own independent blockchains after some time. While this helps them gain better throughput and additional features, the downside lies on the fact that the developer would need to start coding a blockchain from scratch. Even with copying code from another existent blockchain (like a fork), some modifications are needed to differenciate the new blockchain from the original. As such, this would require some knowledge related to how blockchain works specifically.
On the other hand, creating a token only requires you to have a certain level of knowledge of the specific blockchain's programming language. This is much easier, IMO, as you don't need to understand how a blockchain works to implement your own token for the masses to use. Of course, the developer has the option to decide whenever he/she want to deploy a token within an existent blockchain or an independent cryptocurrency.
However, given how popular tokens have become lately, there's a high possibility that they could replace cryptocurrencies in the future. Their success will depend on the specific blockchain they've been launched. If that blockchain is scalable for the masses, then people would use that token at a large scale without hassles. But if the token's underlying blockchain is slow and expensive (like the case of Ethereum), then the best bet for the token to remain useful would be to migrate to its own blockchain.
Nonetheless, only time will tell us whenever tokens have real uses for the mainstream world, or simply cryptocurrencies would take over. Just my opinion