No, toothpaste cannot be put back into the tube. The same way as Islam cannot be reformed. A Pew research done a few years ago showed that around 80% of the followers of the terrorist Muhammad would choose Islam before the host country they migrated to. Their retrograde ideology won't allow them to integrate, and is the reason why many parts of EU which they have flooded have become no go zones for Westerners and Western law.

Whatever happens Europe will change. Everything changes and the history of Europe is one of continuous change.
Even if Islam were to develop much more widely in Europe it would over time be a ‘European’ version which in itself would change. However all this takes time, a lot of time. But what we have currently is an EU which has declared its intention to effectively get rid of the existing Countries. The intention is for Europe to be more like the US ie one big country and at the same time there are millions of (mostly male Muslim) immigrants flooding in. These changes are being imposed on an increasingly reluctant population and opposition is being suppressed. Censorship is increasing and even in the UK which has stepped back from what is happening across the channel political correctness is being imposed and the media is rife with what many see as anti white propaganda. These tactics and the imposition of such change at such a rate is not conducive with peaceful change but the authorities are intent on maintaining their course. If I were a conspiracy theorist I would say that something is setting out to destabilise western society and that many of the politicians are for whatever reason facilitating chaos. One question I always ask when someone denies doing something for nefarious reasons is what they would have done differently if they wanted to avoid the problems they are creating. In this case I cannot see a better way of creating chaos than what is being done.

Nietzsche is right I think in that Muslims in the West and eventually in their hinterlands will also face a vast crisis of faith and belief leading to nihilism in the same way that us in the West has with Christianity as per his ‘Death Of God’ parable etc. Perhaps they see this all too well which explains Islamist ideology as they seek to put the brakes on but the whole structure of Islamic belief is still careering ‘headlong’ down the very same hill as Christianity whether they know it or not, certainly whether they like it or not. They have similar options to us which is to use their religious ideas as placeholders for higher ideals etc as the grounds of Islamic objective truth claims slips from their credulity as well. Probably gonna get messy though as they spin in empty circles firstly blaming our culture and us then themselves as it dawns on them too that the old ideas as presented in the past just won’t work for them anymore and I don’t see even the slightest reform of Islam even starting yet as they desperately cling on shutting their eyes to monsters in the dark like children. The jury is very much out with us as to exactly how we will cope going forward never mind them, overly reliant as they are on simplistic wish fulfilment and unreconstructed 7th century style religiosity.

One will never be certain with Muslims.
In general they mostly come across as peaceful and law abiding
The problem is when something like ISIS pops up, then some of them tend to display their Jihadist sentiments.
The large numbers of refugees is a particular problem as many of these don't speak the language of the country in which they rock up.
They.They are often unemployable and to make matters they don't assimilate in the culture of their new countries.
Their demands sometimes are absurd. Like it's happening in the UK, a liberal, enlightened society is requested to.to tuck it's forelock to the whims and wishes a religion which tenets is rooted in ancient Saudi tribal laws and customs.

The Muslim threat has been thrown off in the seesaw of conflict between the West and Islam since Islam began. Every conflict leaves a little more of humanity conquered by Islam. It will indeed be "the religion of peace" when it has killed off every infidel.
Everyone who understands this will fight them with every ounce of strength.