But, hasn’t been nerfed echo, so the mechwarper-summoning portal-SN1P-SN4P combo is no longer infinite, right?

Yes, because it says “summon” and not “play” (from the hand)

This is also good in wild with Shadow Word: Horror, instead of playing it with Pint-Size Potion.

Is it 100% sure that the duplicate bombs would block this type of effect?

And Tor Tricaster + Shooting Star can be also the same if you need to do 4 damage to only three minion and cost 6