You will burst

When Jesus spoke about new wine and new wineskins, he talked about fasting, and many people do not read that whole passage but extract only the second part. The context shows that practices of Jesus' disciples were perplexing to the religious leaders as the paradigm has shifted from looking at the prescriptive rules to the Person of Christ-focused attention in making decisions about ascetical practices. Jesus here says that when you, as a Beloved, have Him, you, like a new wineskin, have new wine. When you don't, you need to fast to get Him and the purpose of fasting is to change your heart from old to new wineskin, so you can contain new life. In other words, fasting will help you prepare your self as a container for the new Life. Otherwise, you would burst because the Holy One needs more space to expand and only new wineskins are flexible enough to contain bubbling new Life.

Those who ask for the new wine (Holy Spirit) without having new wineskin (their heart, habits, renewed mind, desires, redeemed passions) ready, will burst sooner or later.

The new law fulfills the old by bringing the Maker of the law as the desirable possession.

Mk 2:18-22

The disciples of John and of the Pharisees were accustomed to fast.

People came to Jesus and objected,

“Why do the disciples of John and the disciples of the Pharisees fast,

but your disciples do not fast?”

Jesus answered them,

“Can the wedding guests fast while the bridegroom is with them?

As long as they have the bridegroom with them they cannot fast.

But the days will come when the bridegroom is taken away from them,

and then they will fast on that day.

No one sews a piece of unshrunken cloth on an old cloak.

If he does, its fullness pulls away,

the new from the old, and the tear gets worse.

Likewise, no one pours new wine into old wineskins.

Otherwise, the wine will burst the skins,

and both the wine and the skins are ruined.

Rather, new wine is poured into fresh wineskins.”