I might be wrong (as could be you), but I believe the following.
2014 was the landslide they could ever have got. Anti Incumbency PLUS Modi wave (which the country waited 10 years for while the cases went on).
In 2019
There will also be a degree of anti Incumbency. Not even his biggest bhakt can deny the widespread increasing chorus across the country (and classes) about the lack of hard results on the ground.
Baaton se pet nahin bharta.
Secondly the glow and halo around Modi has definitely reduced from 2014. No one can say he's done a Gujarat at the India level. Economically (communally, he may still live up to his inherent promise).
Lastly the increasing disillusionment and discomfort with the sanghee goons across the country.
And more importantly, no reaction from Modi and his team.
Now look at how he won in 2014. 31% of all votes.
I believe he'll TODAY poll a lot lot less.
In two years time, it will be even lower, cause I do not see things improve from here.
He will lose all but the most die hard Hindu fanatic voter base.
And I also believe that most Hindus are not fanatics.
Not yet at least ...