One should not ignore any jot or tittle in the Bible. One should seek for understanding that makes all words true. Rev 21:5 cannot cancel the other verses above, therefore you must seek to understand a meaning for "all things new" that does not negate the meaning of "eternal fire". Nothing says the some of the old things do not burn forever while a new heaven and new earth are created. Think parallel universes - one with old things burning and one with all things new.

Remember - correct understanding must be able to explain ALL verses. Finding one or two verses that you think support your position cannot wipe out all the others that prove you wrong.