Personally, touring against this SL team will not give much of an indication of the ability of much of this ENG squad. Yes they defeated SA in SA recently but look at how they're faring against ZIM. More than recent results it's how they're playing their cricket - it's very negative. I expected Dickwella, BKG Mendis to really push on but they haven't.
Lakmal and Embuldeniya the spearheads of such an average attack. The likes of Sibley / Crawley / Pope will be out of their comfort zone for sure, but to think this would be anything like playing Pak (A) or Ind (A) would be naive.
Saying that, runs for any of them will only cement their places on future tours but at the same time even if they don't have a great series, I can't see them being binned. I think the ECB will think they've shown enough thus far, and looking at what they've done with the announcement about Mahmood, Stone, Overton - they are looking to invest.