I think SAP HEC is only one of the several alternatives you have to run your SAP applications on the cloud, as you can run SAP on public cloud (e.g. AWS, Azure, Google), private cloud (e.g. SAP HEC, IBM, KIO), and hybrid cloud. Currently SAP itself offers many scenarios to run its applications on cloud according to each SAP Product (e.g. S/4HANA, Success Factors, Ariba), layers to be supported (IaaS, SaaS, PaaS), and your own SAP landscape strategy (e.g. on-premise + cloud, hybrid cloud, backups, DRP, HA). Particularly SAP HEC supports an extensive variety of SAP Products and is offered as an IaaS model, but you can add complementary managed service packages to support also your OS, DB and software. Internally SAP has its own datacenters to deliver SAP HEC, but also subcontracts partner’s datacenters like IBM, NTT, etc. to attend all its SAP HEC demand. SAP HEC is commonly opted by users who want to deal directly with SAP AG and to avoid risks in terms of always keep latest releases, security, response time, performance, compliance, specialization, and control, with no matter of the cost. SAP HEC is not commonly opted by users who are looking for versatility, customization, flexibility, agility, on-demand scaling, own 100% control, and to reduce cost.
When you are choosing a cloud strategy for your SAP landscape, be flexible and careful of the scope, timeline, budget and all of the features and components to be considered as part of the end-to-end cloud strategy.