Monero is just another crypto-currency, but I highly doubt it has enough backing behind it to trump bitcoin. I really dont think any other altcoin can beat bitcoin at this moment. With my little knowledge, I do not expect any tough competitor from altcoins.
But there is a possibility, if something is newly created from scratch (not from bitcoin's basics) and that too have enough facilities to overcome bitcoin's. I guess in near future it will not be possible unless aliens are not ready to help on this.
Yes, Moneros has some power within it still it is so small. I think that if it were upsizes it would be harder to remain the same and may end up with huge dumping then I highly doubt it will remain just another average altcoin. I too want to shout here, bitcoin will not be replaced by any "thing" for sure.