No, that is a lie.  The people who want XT to fail are lying a lot, trying to sabotage the consensus mechanism, etc.  It means they already know that if they are honest they will quickly lose.

XT has been implemented.  Anything that "will happen if XT is implemented" has already happened.

At some point in the future (but not before Jan 2016) the bitcoin protocol may change as a result of XT being adopted by a majority.  If that happens it will not affect the ownership of the coins in your wallet.

What may happen is that some people who have failed or refused to update their software to a client that speaks the new protocol, may reject blocks mined according to that protocol after the changeover date, ultimately forming their own block chain based on the old protocol.  After that, an increasing number of transactions (all transactions involving coins created after the fork) would be valid only in one of the two block chains; the one based on the new rules, or the one based on the old rules.  If you are paid in a transaction that is valid only on one of these two block chains, you may have the coins on that block chain but not on the other.  But this will not affect any coins currently in your wallet; a transaction spending them will be valid according to either version of the rules.

It also won't affect your wealth w/r/t anyone who is using the same set of protocol rules as you; If the transaction where you got coins is confirmed on the block chain that you and someone else both use for a subsequent transaction, a new transaction spending them will also be valid on that same block chain.