I agree that the top 4 battles will be more tightly contested, however in my view that means its going to be even more difficult for the likes of Spurs/Liverpool than ever before (certainly semi consistently). My view is we'll see any one or two of the likes of Leicester, West Ham, So'ton, Everton, Stoke, Liverpool, Spurs etc competing every so often.
The reason for this is that those clubs can compete with and now beat the historic challengers to signings. Going forward West Ham or Leicester may gazzump yourselves to the likes of Erikson, Lamela, Alli, Alderweirald, Firmino, Coutinho etc. From next season there's no reason why West Ham or Leicester can't sell the dream to those type of player and offering them a big salary to go with it (Olympic Stadium, title winners etc). Liverpool and Spurs especially will struggle to keep up with the likes of West Ham with significant stadium debt on the horizon.
However the likes of City, United, Chelsea & Arsenal will still be a league apart in terms of being in for the likes of Sanchez, Ozil, Di Maria, De Bruyne etc who have the greatest chance of success long term. Likewise the best players for the other clubs will still aspire to earning the truly huge (£250k salaries) that only 8 clubs in the world can afford.
Even if we accept the argument that the likes of Kane, Coutinho, Alli won't be allowed to go to a domestic rival. As occurred with Bale it'll "release" a top class player from the likes of Madrid. Kane or Alli go to Madrid, the chances are Benzema, Kroos, Isco and/or James come to England.
Overall it's as easy to see a bleak future for Spurs with the competition they'll face and the stadium debt to pay off and an exciting time for a young, exciting United team with a huge budget and a useless manager leaving.