HESH cannot be delayed due to its very mechanism of operation (It has to flatten out against what it hits), if the HESH beats through, then it would just hit an inside wall, or maybe simply go all the way through and fail to flatten out. HESH could potentially be delayed by a proxy fuse inside the shell though, althouhg you're better off just using HE or HEAT for that purpose. Also, not all future wars will be in places where there is no armored presence, or no structures of extreme strength (i'd keep sabots around, just so I can penetrate the armor of heavily armored AT pillboxes or very heavily reinforced houses.)