Illegal streams in the UK probably do impact attendances - although I acknowledge it is very hard to calculate a number (although no doubt the clubs have tried

).
I know our attendances have officially increased over the last few seasons; but as a season card holder in the North Stand, it has to be said a large number of tickets are being given away cheaply by the club and this inflates the attendance.
With regards to an official service being launched; I am in no doubt that one will come alone in the next 3-5 years. People however will need to realise that these services won't be cheap and certainly won't be priced like the illegal services.
I have NFL game pass which cost me £140 yesterday (or about 30 a month when you consider the length of a NFL season). Although the pass has it faults, in general it's good and allows me to watch the majority of my team's games. HOWEVER

, there are still blackouts should Sky show the game - so if you want to guarantee to watch your team, you need a Sky subscription or a Now TV pass.
If the PL or EFL launched a similar platform, I fully expect the cost to be around £25 a month - but a Sky/BT subscription would still be required to be able to view all the games as TV matches will be subject to blackout.