I don't think 2020 belongs to DEX. Because it still has a long way run to go to beat the current top centralized exchanges. Indeed DEX did improve a lot in past year but still lacks behind in few things which can only be provided by CEX. But when Dex improves their platform or service in the market that might be the reason for them to rise above others in the future.
Agree, 2020 is not the year of DEX and that is not important in my opinion, the most important thing is that DEX and CEX can be accepted by many people and are used massively and safely.
However, you cannot expect much from DEX, because DEX only makes transactions easier so it is impossible to expect DEX services to be better than CEX.
CEX is able to provide many advantages because each trader's funds are stored there, so what DEX services do you expect? when funds are not deposited on the DEX, you don't even need to create an account to trade on DEX.