If a transaction has a fee that is too low then it is possible for the transaction to either age out of the mempool (14 days) or get removed because the mempool reaches its max size. So what happens to that transaction? At some point the transaction is "forgotten" so the sender has the funds available to him again. But how does this happen? Since each miner has its own version of the mempool, is it possible for the transaction to still be in one miner's mempool but not other miners' mempools? How does the network of miners "decide" that the transaction is forgotten so that the sender now has the funds available to him again? And could that person resend that same transaction or does the sender have to create and send a new transaction?
Likely the transaction will be kicked out of the pool - purging it from the node's "memory". Its hard to imagine that there would be a transaction that would qualify for that treatment with one node, but not for others.
But anything is possible.
If that were the case, then that transaction would just remain hanging in the mempool for that particular node that decided to keep it (for whatever reason). For this portion of the protocol though, its more important to take into consideration which action the network would take overall.
How That Specific Node May Handle Things
There's a chance you may attempt to send a duplicate transaction (from the perspective of that node), unwittingly.
Unless you had the RBF flagged ticked for your TX (which there's a good chance that you may have since this is default Electrum behavior along with many other wallets), the node will reject that new transaction attempt since its likely coming a million years after you sent the initial one
Assuming most of the network purged that TX though (they probably did), however that node decides to handle your re-broadcasted TX (if you do that), is neither here nor there