Usually dogecoin is the preferred payment to avoid the large bitcoin fee. people with little financial use of doge as a substitute for a large fee, and in a country known as coin gambling

Yes I really agree on this one most of the people here in crypto world using doge if they will transfer funds to another exchanges less fees and much faster transaction but I doubt it will overtake Bitcoin.
Not for sure, might be BTC will disappear in the future or no one want it due to its overweight and sluggishness. Doge completely an alternative for BTC in trading cryptocurrencies.