Yes Europeans will arrive and they will attempt to colonize the sub continent. Independent movements will arise in the 20th century.
Those facts are not in doubt for an Islamic India would not prevent or alter that. What an Islamic India would alter is how much of Índia is colonized And conquered by Europeans. I could see an Islamic Indian subcontinent being more able to resist Europeans. We could even see European control follow Middle East / North Africa approach where British and French established protectorates instead of actually colonies. These protectorates were ruled individually instead as one colony and people retained link to the traditional rulers
At time of independence each protectorate became separate country. This is how I see the subcontinent not as a single country. So if we want to imagine an Islamic Indian subcontinent then let’s discuss the following
- how it became Islamic,
- how minority religions treated
- Who and to what extent Europeans conquered / colonized / subjuncted the various Indian countries
- What if any part of Indian subcontinent resisted Europeans (could see last parts such as interior) only conquered at end of 19th century.
- How independence movement arise and if they are based on certain nationalities
Now we can imagine an Islamic Indian subcontinent.
Please throw away all preconceived notions that we end up with the same situation as ittl only difference is religion. (Which would not even be homogeneous).